imported>Seamusdemora at 19:21, 28 February 2024

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== Optargs and kwargs aren't varargs ==

Removed from the article for discussion:

:'''''Optional arguments with default values'''''

:''Besides the concept of a ''completely arbitrary number'' of arguments as discussed above, the declaration of '''[[default value]]s''' for ''some'' of the ''specified arguments'' is another concept allowing to call a function with variable number of arguments. Several [[typed language]]s implement this, and can in some cases associate the arguments to the corresponding variables in view of their type, even if they are given at [[call-time]] in an order differing from the declaration. In languages which are not (strongly) typed (such as PHP), such [[optional argument]]s with default values cannot precede [[mandatory]] arguments without default value. (An exception are some system functions of PHP, like [http://php.net/implode the implode function], that can associate arguments given in any order to the right variables, in view of their type.)''

Optional arguments (optargs) do not make a function variadic, even though it may look that way if you examine only the calling code. When a function with optargs is executed, each of the args is bound to some value -- be it a supplied value from the function call, a default value from the function definition, or a null value in the absence of a default value.

The same is true for keyword arguments (kwargs), as in Python or Common Lisp -- a keyword argument gets populated with a value from the call, or it doesn't and defaults to a null value, but it's still bound in the environment under which the function-body is evaluated.

What's going on in variadic functions (varargs, rest args) is that passed-in arguments are ''not'' each used to supply a value for a variable. The handling of the list of passed-in arguments is under the control of the function code itself. Instead of binding a bunch of variables, the arguments are passed in as a list. (Or, in some languages, a list and a length.) This is why C bozos can walk off the end of a varargs list and end up smashing the stack. --[[User:Fubar Obfusco|FOo]] 23:17, 26 May 2005 (UTC)

In the case of Python, isn't this a case of a [[distinction without a difference]] in that a function ends up with a variable number of arguments that it can access. Putting aside the default arguments, Python ''does'' have variadic functions. --[[User:Paddy3118|Paddy]] ([[User talk:Paddy3118|talk]]) 12:48, 23 June 2008 (UTC)

== Variadic functions in C and C++ ==
The code example in this section is not commented at all, nor is there a caption explaining what its purpose is. This should be corrected. --[[User:Walkeraj|Walkeraj]] 22:06, 3 October 2007 (UTC)
:...and a C example would also be nice, especially because there exists the [[variadic macro]] article. --[[User:Abdull|Abdull]] 09:17, 4 December 2007 (UTC)

I was hoping to find an example here of how to create a variadic function wrapping another such function.

Label *createLabel(Object *owner, const char * format, ...) {
char labelDescription[200];
snprintf(labelDescription, 200, format, /* What goes here?? */);
return new Label(owner, labelDescription);
}

[[Special:Contributions/99.67.239.69|99.67.239.69]] ([[User talk:99.67.239.69|talk]]) 01:09, 3 May 2011 (UTC)

: Use vsnprintf(): https://en.cppreference.com/w/c/io/vfprintf --[[Special:Contributions/2003:E3:B725:FC00:71C9:1666:9CE0:20D9|2003:E3:B725:FC00:71C9:1666:9CE0:20D9]] ([[User talk:2003:E3:B725:FC00:71C9:1666:9CE0:20D9|talk]]) 12:41, 11 May 2022 (UTC)

== manual tag ==

I've added the {{[[Template:manual|manual]]}} tag to the section on specific implementations. A brief, prose overview with perhaps one or two examples might be useful, but what we have is just a sprawling reference manual on how to use variadic parameter passing in multiple languages, and that's not what a Wikipedia article is for. -[[User:Miskaton|Miskaton]] ([[User talk:Miskaton|talk]]) 12:54, 11 April 2008 (UTC)
: I agree. Considering that no-one has objected in the past 3 years, I'm going to remove all the notes about specific implementations -- each language which support variadic functions should have their own section about it, instead of having a large collection of semi-useful often poorly written sections here. [[Special:Contributions/80.162.60.16|80.162.60.16]] ([[User talk:80.162.60.16|talk]]) 13:08, 23 July 2011 (UTC)

: I would prefer you remove them and instead reference the newly added Rosetta Code task from the external links section. --[[User:Paddy3118|Paddy]] ([[User talk:Paddy3118|talk]]) 06:31, 24 July 2011 (UTC)

==Vararg function implementations can be divided into 3 classes==
What is the use of such a classification?<br>The list on its own is of very little use and should be deleted. --[[User:Paddy3118|Paddy]] ([[User talk:Paddy3118|talk]]) 05:35, 30 July 2010 (UTC)

== Usefulness of vadiadic functions? ==

Is there any advantage to using a vadiadic function over say, a list? Perhaps it's more useful in a language like C where you can't construct lists easily? What are the advantages/disadvantages? Language bloat? <span style="font-size: smaller;" class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/99.224.181.247|99.224.181.247]] ([[User talk:99.224.181.247|talk]]) 00:16, 12 May 2011 (UTC)</span>

Talk:Variadic function - Revision history

imported>Seamusdemora at 19:21, 28 February 2024