2019-02-04 22:26:45 +00:00
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
< html >
< head >
2020-04-08 22:41:00 +00:00
< title > Methods< / title >
2020-04-23 22:23:44 +00:00
< link href = "../docs-assets/Breadcrumbs.css" rel = "stylesheet" rev = "stylesheet" type = "text/css" >
2020-03-19 00:03:04 +00:00
< meta name = "viewport" content = "width=device-width initial-scale=1" >
2019-02-04 22:26:45 +00:00
< meta http-equiv = "Content-Type" content = "text/html; charset=utf-8" >
< meta http-equiv = "Content-Language" content = "en-gb" >
2020-04-20 22:26:08 +00:00
2020-05-02 22:50:23 +00:00
< link href = "../docs-assets/Contents.css" rel = "stylesheet" rev = "stylesheet" type = "text/css" >
2020-04-30 22:36:38 +00:00
< link href = "../docs-assets/Progress.css" rel = "stylesheet" rev = "stylesheet" type = "text/css" >
2020-04-25 10:33:39 +00:00
< link href = "../docs-assets/Navigation.css" rel = "stylesheet" rev = "stylesheet" type = "text/css" >
< link href = "../docs-assets/Fonts.css" rel = "stylesheet" rev = "stylesheet" type = "text/css" >
2020-04-20 22:26:08 +00:00
< link href = "../docs-assets/Base.css" rel = "stylesheet" rev = "stylesheet" type = "text/css" >
2020-04-21 16:55:17 +00:00
< link href = "../docs-assets/Colours.css" rel = "stylesheet" rev = "stylesheet" type = "text/css" >
2020-04-23 22:23:44 +00:00
2019-02-04 22:26:45 +00:00
< / head >
2020-04-25 10:33:39 +00:00
< body class = "commentary-font" >
2020-03-19 00:03:04 +00:00
< nav role = "navigation" >
2020-04-13 16:06:45 +00:00
< h1 > < a href = "../index.html" >
2020-04-20 22:26:08 +00:00
< img src = "../docs-assets/Octagram.png" width = 72 height = 72" >
2020-04-13 16:06:45 +00:00
< / a > < / h1 >
< ul > < li > < a href = "../inweb/index.html" > inweb< / a > < / li >
< / ul > < h2 > Foundation Module< / h2 > < ul >
< li > < a href = "index.html" > < span class = "selectedlink" > foundation< / span > < / a > < / li >
2020-03-19 00:03:04 +00:00
< li > < a href = "../foundation-test/index.html" > foundation-test< / a > < / li >
2020-04-13 16:06:45 +00:00
< / ul > < h2 > Example Webs< / h2 > < ul >
2020-04-12 16:24:23 +00:00
< li > < a href = "../goldbach/index.html" > goldbach< / a > < / li >
< li > < a href = "../twinprimes/twinprimes.html" > twinprimes< / a > < / li >
2020-04-15 22:45:08 +00:00
< li > < a href = "../eastertide/index.html" > eastertide< / a > < / li >
2020-04-14 17:36:42 +00:00
< / ul > < h2 > Repository< / h2 > < ul >
2020-04-20 22:34:44 +00:00
< li > < a href = "https://github.com/ganelson/inweb" > < img src = "../docs-assets/github.png" height = 18 > github< / a > < / li >
2020-04-14 17:36:42 +00:00
< / ul > < h2 > Related Projects< / h2 > < ul >
< li > < a href = "../../../inform/docs/index.html" > inform< / a > < / li >
< li > < a href = "../../../intest/docs/index.html" > intest< / a > < / li >
2020-03-19 00:03:04 +00:00
2020-04-13 16:06:45 +00:00
< / ul >
2020-03-19 00:03:04 +00:00
< / nav >
< main role = "main" >
2020-04-23 22:23:44 +00:00
<!-- Weave of 'Methods' generated by Inweb -->
2020-04-30 22:36:38 +00:00
< div class = "breadcrumbs" >
< ul class = "crumbs" > < li > < a href = "../index.html" > Home< / a > < / li > < li > < a href = "index.html" > foundation< / a > < / li > < li > < a href = "index.html#2" > Chapter 2: Memory, Streams and Collections< / a > < / li > < li > < b > Methods< / b > < / li > < / ul > < / div >
< p class = "purpose" > General support for something approximating method calls.< / p >
2019-02-04 22:26:45 +00:00
2020-05-09 12:05:00 +00:00
< ul class = "toc" > < li > < a href = "2-mth.html#SP1" > § 1. Method sets< / a > < / li > < li > < a href = "2-mth.html#SP3" > § 3. Declaring methods< / a > < / li > < li > < a href = "2-mth.html#SP5" > § 5. Adding methods< / a > < / li > < li > < a href = "2-mth.html#SP6" > § 6. Calling methods< / a > < / li > < / ul > < hr class = "tocbar" >
2019-02-04 22:26:45 +00:00
2020-08-16 17:39:53 +00:00
< p class = "commentary firstcommentary" > < a id = "SP1" class = "paragraph-anchor" > < / a > < b > § 1. Method sets. < / b > This section provides a very rudimentary implementation of method calls,
2019-02-04 22:26:45 +00:00
ordinarily not available in C, but doesn't pretend to offer the full
functionality of an object-oriented language.
< / p >
2020-04-24 23:06:02 +00:00
< p class = "commentary" > Instead, it's really intended for protocol-based coding patterns. Suppose that
2019-02-04 22:26:45 +00:00
we have objects of several different structure types, but all of them can
serve a given purpose — say, all of them contribute an adjective to the
Inform language. What we want is the ability to take a pointer, which might be
to an object of any of these types, and to tell the object to do something, or
ask it a question.
< / p >
2020-04-24 23:06:02 +00:00
< p class = "commentary" > Alternatively, we may have a situation where there are multiple objects of the
2019-02-04 22:26:45 +00:00
same type which each represent a different way of doing something: for
example, in the Inweb source code, each different supported programming
language is represented by an object. These objects need to encapsulate all
the ways that one language differs from another, and they can do that by
providing "methods".
< / p >
2020-08-16 17:39:53 +00:00
< p class = "commentary firstcommentary" > < a id = "SP2" class = "paragraph-anchor" > < / a > < b > § 2. < / b > A "method set" is simply a linked list of methods:
2019-02-04 22:26:45 +00:00
< / p >
2020-04-25 10:33:39 +00:00
< pre class = "displayed-code all-displayed-code code-font" >
2020-04-21 16:55:17 +00:00
< span class = "reserved-syntax" > typedef< / span > < span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > struct< / span > < span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > method_set< / span > < span class = "plain-syntax" > {< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > struct< / span > < span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > method< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > first_method< / span > < span class = "plain-syntax" > ;< / span >
2020-05-09 12:05:00 +00:00
< span class = "plain-syntax" > < / span > < span class = "constant-syntax" > CLASS_DEFINITION< / span >
2020-04-21 16:55:17 +00:00
< span class = "plain-syntax" > } < / span > < span class = "reserved-syntax" > method_set< / span > < span class = "plain-syntax" > ;< / span >
2020-05-09 12:05:00 +00:00
< span class = "reserved-syntax" > method_set< / span > < span class = "plain-syntax" > *< / span > < span class = "function-syntax" > Methods::new_set< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > ) {< / span >
2020-04-21 16:55:17 +00:00
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > method_set< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > S< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > CREATE< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > method_set< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > S< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > first_method< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > S< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
2020-04-24 10:26:18 +00:00
< / pre >
< ul class = "endnotetexts" > < li > The structure method_set is private to this section.< / li > < / ul >
2020-08-16 17:39:53 +00:00
< p class = "commentary firstcommentary" > < a id = "SP3" class = "paragraph-anchor" > < / a > < b > § 3. Declaring methods. < / b > Each method is a function, though we don't know its type — which is why we
2020-04-22 22:57:09 +00:00
resort to the desperate measure of storing it as a < span class = "extract" > < span class = "extract-syntax" > void *< / span > < / span > — with an ID
number attached to it. IDs should be from the < span class = "extract" > < span class = "extract-syntax" > *_MTID< / span > < / span > enumeration set.
2019-02-04 22:26:45 +00:00
< / p >
2020-04-25 10:33:39 +00:00
< pre class = "definitions code-font" > < span class = "definition-keyword" > enum< / span > < span class = "constant-syntax" > UNUSED_METHOD_ID_MTID< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > from< / span > < span class = "plain-syntax" > < / span > < span class = "constant-syntax" > 1< / span >
2019-02-04 22:26:45 +00:00
< / pre >
2020-08-16 17:39:53 +00:00
< p class = "commentary firstcommentary" > < a id = "SP4" class = "paragraph-anchor" > < / a > < b > § 4. < / b > The type of a method must neverthess be specified, and we do it with one
2019-02-04 22:26:45 +00:00
of two macros: one for methods returning an integer, one for void methods,
i.e., those returning no value.
< / p >
2020-04-24 23:06:02 +00:00
< p class = "commentary" > What these do is to use typedef to give the name < span class = "extract" > < span class = "extract-syntax" > X_type< / span > < / span > to the type of all
2020-04-22 22:57:09 +00:00
functions sharing the method ID < span class = "extract" > < span class = "extract-syntax" > X< / span > < / span > .
2019-02-04 22:26:45 +00:00
< / p >
2020-05-09 12:05:00 +00:00
< pre class = "definitions code-font" > < span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > INT_METHOD_TYPE< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > id< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > args< / span > < span class = "plain-syntax" > ...)< / span >
2020-04-24 10:26:18 +00:00
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > typedef< / span > < span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > (*< / span > < span class = "identifier-syntax" > id< / span > < span class = "plain-syntax" > ##< / span > < span class = "identifier-syntax" > _type< / span > < span class = "plain-syntax" > )(< / span > < span class = "identifier-syntax" > args< / span > < span class = "plain-syntax" > );< / span >
2020-05-09 12:05:00 +00:00
< span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > VOID_METHOD_TYPE< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > id< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > args< / span > < span class = "plain-syntax" > ...)< / span >
2020-04-24 10:26:18 +00:00
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > typedef< / span > < span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > (*< / span > < span class = "identifier-syntax" > id< / span > < span class = "plain-syntax" > ##< / span > < span class = "identifier-syntax" > _type< / span > < span class = "plain-syntax" > )(< / span > < span class = "identifier-syntax" > args< / span > < span class = "plain-syntax" > );< / span >
2019-02-04 22:26:45 +00:00
< / pre >
2020-04-25 10:33:39 +00:00
< pre class = "displayed-code all-displayed-code code-font" >
2020-05-09 12:05:00 +00:00
< span class = "identifier-syntax" > INT_METHOD_TYPE< / span > < span class = "plain-syntax" > (< / span > < span class = "constant-syntax" > UNUSED_METHOD_ID_MTID< / span > < span class = "plain-syntax" > , < / span > < span class = "reserved-syntax" > text_stream< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > example< / span > < span class = "plain-syntax" > , < / span > < span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > wont_be_used< / span > < span class = "plain-syntax" > )< / span >
2020-04-24 10:26:18 +00:00
< / pre >
2020-08-16 17:39:53 +00:00
< p class = "commentary firstcommentary" > < a id = "SP5" class = "paragraph-anchor" > < / a > < b > § 5. Adding methods. < / b > Provided a function has the right type for the ID we're using, we can now
2020-04-22 22:57:09 +00:00
attach it to an object with a method set, using the < span class = "extract" > < span class = "extract-syntax" > METHOD_ADD< / span > < / span > macro.
2019-02-04 22:26:45 +00:00
(If the type is wrong, the C compiler will throw errors here.)
< / p >
2020-04-25 10:33:39 +00:00
< pre class = "definitions code-font" > < span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > METHOD_ADD< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > upon< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > id< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > func< / span > < span class = "plain-syntax" > )< / span >
2020-05-09 12:05:00 +00:00
< span class = "plain-syntax" > < / span > < a href = "2-mth.html#SP5" class = "function-link" > < span class = "function-syntax" > Methods::add< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > upon< / span > < span class = "plain-syntax" > -> < / span > < span class = "identifier-syntax" > methods< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > id< / span > < span class = "plain-syntax" > , (< / span > < span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > *) & < / span > < span class = "identifier-syntax" > func< / span > < span class = "plain-syntax" > );< / span >
2019-02-04 22:26:45 +00:00
< / pre >
2020-04-25 10:33:39 +00:00
< pre class = "displayed-code all-displayed-code code-font" >
2020-04-21 16:55:17 +00:00
< span class = "reserved-syntax" > typedef< / span > < span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > struct< / span > < span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > method< / span > < span class = "plain-syntax" > {< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > method_id< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > method_function< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > struct< / span > < span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > method< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > next_method< / span > < span class = "plain-syntax" > ;< / span >
2020-05-09 12:05:00 +00:00
< span class = "plain-syntax" > < / span > < span class = "constant-syntax" > CLASS_DEFINITION< / span >
2020-04-21 16:55:17 +00:00
< span class = "plain-syntax" > } < / span > < span class = "reserved-syntax" > method< / span > < span class = "plain-syntax" > ;< / span >
2020-04-25 12:26:09 +00:00
< span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > < / span > < span class = "function-syntax" > Methods::add< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > method_set< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > S< / span > < span class = "plain-syntax" > , < / span > < span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > ID< / span > < span class = "plain-syntax" > , < / span > < span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > function< / span > < span class = "plain-syntax" > ) {< / span >
2020-04-21 16:55:17 +00:00
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > method< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > CREATE< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > method< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > method_id< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > ID< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > method_function< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > function< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > next_method< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > S< / span > < span class = "plain-syntax" > -> < / span > < span class = "identifier-syntax" > first_method< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ) < / span > < span class = "identifier-syntax" > S< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > first_method< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > else< / span > < span class = "plain-syntax" > {< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > method< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > existing< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > S< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > first_method< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > while< / span > < span class = "plain-syntax" > ((< / span > < span class = "identifier-syntax" > existing< / span > < span class = "plain-syntax" > ) & & (< / span > < span class = "identifier-syntax" > existing< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > next_method< / span > < span class = "plain-syntax" > )) < / span > < span class = "identifier-syntax" > existing< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > existing< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > next_method< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > existing< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > next_method< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
< span class = "plain-syntax" > }< / span >
2020-04-25 12:26:09 +00:00
< span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "function-syntax" > Methods::provided< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > method_set< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > S< / span > < span class = "plain-syntax" > , < / span > < span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > ID< / span > < span class = "plain-syntax" > ) {< / span >
2020-04-21 16:55:17 +00:00
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > S< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ) < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < span class = "constant-syntax" > FALSE< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > for< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > method< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > S< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > first_method< / span > < span class = "plain-syntax" > ; < / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > ; < / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > next_method< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > method_id< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > ID< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < span class = "constant-syntax" > TRUE< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < span class = "constant-syntax" > FALSE< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
2020-04-24 10:26:18 +00:00
< / pre >
< ul class = "endnotetexts" > < li > The structure method is private to this section.< / li > < / ul >
2020-08-16 17:39:53 +00:00
< p class = "commentary firstcommentary" > < a id = "SP6" class = "paragraph-anchor" > < / a > < b > § 6. Calling methods. < / b > Method calls are also done with a macro, but it has to come in four variants:
2020-04-24 10:26:18 +00:00
< / p >
2020-05-09 12:05:00 +00:00
< ul class = "items" > < li > (a) < span class = "extract" > < span class = "extract-syntax" > INT_METHOD_CALL< / span > < / span > for a method taking arguments and returning an < span class = "extract" > < span class = "extract-syntax" > int< / span > < / span > ,
< / li > < li > (b) < span class = "extract" > < span class = "extract-syntax" > INT_METHOD_CALL_WITHOUT_ARGUMENTS< / span > < / span > for a method without arguments which returns an < span class = "extract" > < span class = "extract-syntax" > int< / span > < / span > ,
< / li > < li > (c) < span class = "extract" > < span class = "extract-syntax" > VOID_METHOD_CALL< / span > < / span > for a method taking arguments and returning nothing,
< / li > < li > (d) < span class = "extract" > < span class = "extract-syntax" > VOID_METHOD_CALL_WITHOUT_ARGUMENTS< / span > < / span > for a method without arguments which returns nothing.
2020-04-24 23:06:02 +00:00
< / li > < / ul >
< p class = "commentary" > For example:
2020-04-24 10:26:18 +00:00
< / p >
2020-04-25 10:33:39 +00:00
< pre class = "displayed-code all-displayed-code code-font" >
2020-05-09 12:05:00 +00:00
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > INT_METHOD_CALL< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > some_object< / span > < span class = "plain-syntax" > , < / span > < span class = "constant-syntax" > UNUSED_METHOD_ID_MTID< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > I< / span > < span class = "string-syntax" > "Hello"< / span > < span class = "plain-syntax" > , < / span > < span class = "constant-syntax" > 17< / span > < span class = "plain-syntax" > )< / span >
2019-02-04 22:26:45 +00:00
< / pre >
2020-04-24 23:06:02 +00:00
< p class = "commentary" > Note that it's entirely possible for the < span class = "extract" > < span class = "extract-syntax" > upon< / span > < / span > object to have multiple methods
2020-04-22 22:57:09 +00:00
added for the same ID — or none. In the < span class = "extract" > < span class = "extract-syntax" > V< / span > < / span > (void) cases, what we then do is
to call each of them in turn. In the < span class = "extract" > < span class = "extract-syntax" > I< / span > < / span > (int) cases, we call each in turn, but
stop the moment any of them returns something other than < span class = "extract" > < span class = "extract-syntax" > FALSE< / span > < / span > , and then
we put that value into the specified result variable < span class = "extract" > < span class = "extract-syntax" > rval< / span > < / span > .
2019-02-04 22:26:45 +00:00
< / p >
2020-04-24 23:06:02 +00:00
< p class = "commentary" > If < span class = "extract" > < span class = "extract-syntax" > some_object< / span > < / span > has no methods for the given ID, then nothing happens, and
2020-04-22 22:57:09 +00:00
in the < span class = "extract" > < span class = "extract-syntax" > I< / span > < / span > case, the return value is < span class = "extract" > < span class = "extract-syntax" > FALSE< / span > < / span > .
2019-02-04 22:26:45 +00:00
< / p >
2020-04-24 23:06:02 +00:00
< p class = "commentary" > It will, however, produce a compilation error if < span class = "extract" > < span class = "extract-syntax" > some_object< / span > < / span > is not a pointer
2020-06-29 22:42:03 +00:00
to a structure which has a < span class = "extract" > < span class = "extract-syntax" > methods< / span > < / span > element as part of its definition.
2019-02-04 22:26:45 +00:00
< / p >
2020-05-09 12:05:00 +00:00
< pre class = "definitions code-font" > < span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > INT_METHOD_CALL< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > rval< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > upon< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > id< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > args< / span > < span class = "plain-syntax" > ...) {< / span >
2020-04-24 10:26:18 +00:00
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > rval< / span > < span class = "plain-syntax" > = < / span > < span class = "constant-syntax" > FALSE< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > for< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > method< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > upon< / span > < span class = "plain-syntax" > ?(< / span > < span class = "identifier-syntax" > upon< / span > < span class = "plain-syntax" > -> < / span > < span class = "identifier-syntax" > methods< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > first_method< / span > < span class = "plain-syntax" > ):< / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ; < / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > ; < / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > next_method< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > method_id< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > id< / span > < span class = "plain-syntax" > ) {< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > method_rval_< / span > < span class = "plain-syntax" > = (*((< / span > < span class = "identifier-syntax" > id< / span > < span class = "plain-syntax" > ##< / span > < span class = "identifier-syntax" > _type< / span > < span class = "plain-syntax" > ) (< / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > method_function< / span > < span class = "plain-syntax" > )))(< / span > < span class = "identifier-syntax" > upon< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > args< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > method_rval_< / span > < span class = "plain-syntax" > ) {< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > rval< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > method_rval_< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > break< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
< span class = "plain-syntax" > }< / span >
< span class = "plain-syntax" > }< / span >
2020-05-09 12:05:00 +00:00
< span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > INT_METHOD_CALL_WITHOUT_ARGUMENTS< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > rval< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > upon< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > id< / span > < span class = "plain-syntax" > ) {< / span >
2020-04-24 10:26:18 +00:00
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > rval< / span > < span class = "plain-syntax" > = < / span > < span class = "constant-syntax" > FALSE< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > for< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > method< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > upon< / span > < span class = "plain-syntax" > ?(< / span > < span class = "identifier-syntax" > upon< / span > < span class = "plain-syntax" > -> < / span > < span class = "identifier-syntax" > methods< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > first_method< / span > < span class = "plain-syntax" > ):< / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ; < / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > ; < / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > next_method< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > method_id< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > id< / span > < span class = "plain-syntax" > ) {< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > method_rval_< / span > < span class = "plain-syntax" > = (*((< / span > < span class = "identifier-syntax" > id< / span > < span class = "plain-syntax" > ##< / span > < span class = "identifier-syntax" > _type< / span > < span class = "plain-syntax" > ) (< / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > method_function< / span > < span class = "plain-syntax" > )))(< / span > < span class = "identifier-syntax" > upon< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > method_rval_< / span > < span class = "plain-syntax" > ) {< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > rval< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > method_rval_< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > break< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
< span class = "plain-syntax" > }< / span >
< span class = "plain-syntax" > }< / span >
2020-05-09 12:05:00 +00:00
< span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > VOID_METHOD_CALL< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > upon< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > id< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > args< / span > < span class = "plain-syntax" > ...)< / span >
2020-04-24 10:26:18 +00:00
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > for< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > method< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > upon< / span > < span class = "plain-syntax" > ?(< / span > < span class = "identifier-syntax" > upon< / span > < span class = "plain-syntax" > -> < / span > < span class = "identifier-syntax" > methods< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > first_method< / span > < span class = "plain-syntax" > ):< / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ; < / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > ; < / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > next_method< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > method_id< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > id< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > (*((< / span > < span class = "identifier-syntax" > id< / span > < span class = "plain-syntax" > ##< / span > < span class = "identifier-syntax" > _type< / span > < span class = "plain-syntax" > ) (< / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > method_function< / span > < span class = "plain-syntax" > )))(< / span > < span class = "identifier-syntax" > upon< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > args< / span > < span class = "plain-syntax" > );< / span >
2020-05-09 12:05:00 +00:00
< span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > VOID_METHOD_CALL_WITHOUT_ARGUMENTS< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > upon< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > id< / span > < span class = "plain-syntax" > )< / span >
2020-04-24 10:26:18 +00:00
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > for< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > method< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > upon< / span > < span class = "plain-syntax" > ?(< / span > < span class = "identifier-syntax" > upon< / span > < span class = "plain-syntax" > -> < / span > < span class = "identifier-syntax" > methods< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > first_method< / span > < span class = "plain-syntax" > ):< / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ; < / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > ; < / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > next_method< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > method_id< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > id< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > (*((< / span > < span class = "identifier-syntax" > id< / span > < span class = "plain-syntax" > ##< / span > < span class = "identifier-syntax" > _type< / span > < span class = "plain-syntax" > ) (< / span > < span class = "identifier-syntax" > M< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > method_function< / span > < span class = "plain-syntax" > )))(< / span > < span class = "identifier-syntax" > upon< / span > < span class = "plain-syntax" > );< / span >
2019-02-04 22:26:45 +00:00
< / pre >
2020-04-30 22:36:38 +00:00
< nav role = "progress" > < div class = "progresscontainer" >
2020-07-04 19:28:54 +00:00
< ul class = "progressbar" > < li class = "progressprev" > < a href = "2-wal.html" > ❮ < / a > < / li > < li class = "progresschapter" > < a href = "P-abgtf.html" > P< / a > < / li > < li class = "progresschapter" > < a href = "1-fm.html" > 1< / a > < / li > < li class = "progresscurrentchapter" > 2< / li > < li class = "progresssection" > < a href = "2-dl.html" > dl< / a > < / li > < li class = "progresssection" > < a href = "2-mmr.html" > mmr< / a > < / li > < li class = "progresssection" > < a href = "2-fc.html" > fc< / a > < / li > < li class = "progresssection" > < a href = "2-lcl.html" > lcl< / a > < / li > < li class = "progresssection" > < a href = "2-str.html" > str< / a > < / li > < li class = "progresssection" > < a href = "2-wal.html" > wal< / a > < / li > < li class = "progresscurrent" > mth< / li > < li class = "progresssection" > < a href = "2-llas.html" > llas< / a > < / li > < li class = "progresssection" > < a href = "2-dct.html" > dct< / a > < / li > < li class = "progresssection" > < a href = "2-trs.html" > trs< / a > < / li > < li class = "progresschapter" > < a href = "3-em.html" > 3< / a > < / li > < li class = "progresschapter" > < a href = "4-chr.html" > 4< / a > < / li > < li class = "progresschapter" > < a href = "5-htm.html" > 5< / a > < / li > < li class = "progresschapter" > < a href = "6-bf.html" > 6< / a > < / li > < li class = "progresschapter" > < a href = "7-vn.html" > 7< / a > < / li > < li class = "progresschapter" > < a href = "8-ws.html" > 8< / a > < / li > < li class = "progressnext" > < a href = "2-llas.html" > ❯ < / a > < / li > < / ul > < / div >
2020-04-30 22:36:38 +00:00
< / nav > <!-- End of weave -->
2020-04-23 22:23:44 +00:00
2020-03-19 00:03:04 +00:00
< / main >
2019-02-04 22:26:45 +00:00
< / body >
< / html >
