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(Coding Conventions): Separate defvar and require

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methods to avoid warnings.  Use require only when there are many
functions and variables from that package.
This commit is contained in:
Richard M. Stallman 2004-11-16 17:30:48 +00:00
parent 5d64585238
commit 155cb2e57e
1 changed files with 22 additions and 13 deletions
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35
lispref/tips.texi
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@ -370,25 +370,34 @@ coherent if all libraries use the same conventions.
@item
Try to avoid compiler warnings about undefined free variables, by adding
@code{defvar} definitions for these variables.
dummy @code{defvar} definitions for these variables, like this:
Sometimes adding a @code{require} for another package is useful to avoid
compilation warnings for variables and functions defined in that
package. If you do this, often it is better if the @code{require} acts
only at compile time. Here's how to do that:
@example
(defvar foo)
@end example
Such a definition has no effect except to tell the compiler
not to warn about uses of the variable @code{foo} in this file.
@item
If you use many functions and variables from a certain file, you can
add a @code{require} for that package to avoid compilation warnings
for them. It is better if the @code{require} acts only at compile
time. Here's how to do this:
@example
(eval-when-compile
(require 'foo)
(defvar bar-baz))
(require 'foo))
@end example
If you bind a variable in one function, and use it or set it in another
function, the compiler warns about the latter function unless the
variable has a definition. But often these variables have short names,
and it is not clean for Lisp packages to define such variable names.
Therefore, you should rename the variable to start with the name prefix
used for the other functions and variables in your package.
@item
If you bind a variable in one function, and use it or set it in
another function, the compiler warns about the latter function unless
the variable has a definition. But adding a definition would be
unclean if the variable has a short names, since Lisp packages should
not define short variable names. The right thing to do is to rename
this variable to start with the name prefix used for the other
functions and variables in your package.
@item
Indent each function with @kbd{C-M-q} (@code{indent-sexp}) using the