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Diffstat (limited to 'doc/gawk.texi')
| -rw-r--r-- | doc/gawk.texi | 46 |
1 files changed, 38 insertions, 8 deletions
diff --git a/doc/gawk.texi b/doc/gawk.texi index b08231df..7eb90db2 100644 --- a/doc/gawk.texi +++ b/doc/gawk.texi @@ -19,11 +19,6 @@ * awk: (gawk)Invoking Gawk. Text scanning and processing. @end direntry -@c Enable better indexing, requires texindex from Texinfo 6 or later. -@tex -\global\usebracesinindexestrue -@end tex - @ifset FOR_PRINT @tex \gdef\xrefprintnodename#1{``#1''} @@ -772,10 +767,11 @@ particular records in a file and perform operations upon them. mean. * Function Example:: An example function definition and what it does. -* Function Caveats:: Things to watch out for. +* Function Calling:: Calling user-defined functions. * Calling A Function:: Don't use spaces. * Variable Scope:: Controlling variable scope. * Pass By Value/Reference:: Passing parameters. +* Function Caveats:: Other points to know about functions. * Return Statement:: Specifying the value a function returns. * Dynamic Typing:: How variable types can change at @@ -20499,7 +20495,7 @@ them (i.e., to tell @command{awk} what they should do). * Definition Syntax:: How to write definitions and what they mean. * Function Example:: An example function definition and what it does. -* Function Caveats:: Things to watch out for. +* Function Calling:: Calling user-defined functions. * Return Statement:: Specifying the value a function returns. * Dynamic Typing:: How variable types can change at runtime. @end menu @@ -20773,7 +20769,7 @@ for its format string. That would be a mistake, because @code{ctime()} is supposed to return the time formatted in a standard fashion, and user-level code could have changed @code{PROCINFO["strftime"]}. -@node Function Caveats +@node Function Calling @subsection Calling User-Defined Functions @cindex functions, user-defined, calling @@ -20785,6 +20781,7 @@ the function. * Calling A Function:: Don't use spaces. * Variable Scope:: Controlling variable scope. * Pass By Value/Reference:: Passing parameters. +* Function Caveats:: Other points to know about functions. @end menu @node Calling A Function @@ -21031,6 +21028,9 @@ prints @samp{a[1] = 1, a[2] = two, a[3] = 3}, because @code{changeit()} stores @code{"two"} in the second element of @code{a}. @end quotation +@node Function Caveats +@subsubsection Other Points About Calling Functions + @cindex undefined functions @cindex functions, undefined Some @command{awk} implementations allow you to call a function that @@ -21072,6 +21072,36 @@ or the @code{nextfile} statement inside a user-defined function. @command{gawk} does not have this limitation. +You can call a function and pass it more parameters than it was declared +with, like so: + +@example +function foo(p1, p2) +@{ + @dots{} +@} + +BEGIN @{ + foo(1, 2, 3, 4) +@} +@end example + +Doing so is bad practice, however. The called function cannot do +anything with the additional values being passed to it, so @command{awk} +evaluates the expressions but then just throws them away. + +More importantly, such a call is confusing for whoever will next read your +program.@footnote{Said person might even be you, sometime in the future, +at which point you will wonder, ``what was I thinking?!?''} Function +parameters generally are input items that influence the computation +performed by the function. Calling a function with more paramaters than +it accepts gives the false impression that those values are important +to the function, when in fact they are not. + +Because this is such a bad practice, @command{gawk} @emph{unconditionally} +issues a warning whenever it executes such a function call. (If you +don't like the warning, fix your code! It's incorrect, after all.) + @node Return Statement @subsection The @code{return} Statement @cindex @code{return} statement@comma{} user-defined functions |