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Re: Do function arguments invoke a function?

Cross-posted to 2 groups.

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On 10/04/2015 01:19 PM, Stefan Ram wrote:
> Newsgroups: comp.lang.c,comp.lang.java.programmer
> 
> James Kuyper <jameskuyper@verizon.net> writes:
>> On 10/04/2015 05:15 AM, Chad wrote:
> 
>>> In Java, when a method is called, the methods arguments invoke the method.
>      ^^^^ thus the Newsgroups header!
> 
>> Could you explain what that phrase "the method's arguments invoke the
>> method" means to you? Knowing that, I might be able to answer with
>> respect to C. As it stands, the phrase doesn't make sense to me.
> 
>   You are right!
> 
>   To »invoke« means to start, to execute, to run something. Arguments are
>   expressions that can be part of a method invocation expression.

OK - it's just as true in C/C++ that the argument of a function can be
the result of evaluating an expression. I hadn't thought of his question
in those terms. In that sense, in C++ an argument expression can invoke
methods associated with the objects involved in the expression, and can
invoke methods associated with the same class that the calling method is
associated with, even including another instance of the same method.
However, they cannot be said, in any sense, to invoke the same instance
of that method which they themselves are arguments of. It's the calling
code that does that invocation, not the arguments.

Evaluation of all method arguments must be complete, before evaluation
of the method itself can start, so it's never the case that the
arguments themselves invoke the instance of the method that they
themselves are arguments to. Does Java have different rules in this
regard that would make Chad's comment meaningful?

>  For example, in Java, the following is an expression:
> 
> java.lang.Math.random()
> 
>   . This method invocation expression (JLS 15.12) has no arguments.
>   If the method's arguments would invoke the method, it would not
>   be invoked here, since there are no arguments.
> 
>   Moreover, a method does not have arguments in Java at all. It has
>   /parameters/. A /method invocation expression/ has arguments.

That distinction applies to C/C++ as well.

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Re: Do function arguments invoke a function? James Kuyper <jameskuyper@verizon.net> - 2015-10-04 14:36 -0400

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