Re: Starting out with sub-procedures

[James Rich <james@xxxxxxxxxxx>]

jt wrote:

> |   >> But if the procedure is written in another language, then those
> | languages do not have a PI defined so there is no checking until run time.
> |
> | All languages have the equivalent of a PI (RPG's *ENTRY PLIST is the same
> | thing with different syntax) but not all have prototyping - notably CL and
> | COBOL do not.
>
> C has prototyping?  Does the RPGLE compiler validate against the C
> prototype???

Yes, C has prototyping.  In fact C is one of the languages with the 
strongest prototyping.  A prototype in C looks like:

int function (char variable1, int variable2);

That is the equivalent of the PR spec in RPG.  And yes, the ILE compiler 
validates the C prototype.

> | The real problem with this statement however is "there is no
> | checking until
> | run time".  Leave out the words "until run time" and the statement is
> | accurate.  i.e. "there is no checking".  The reason that prototyping is
> | valuable is _because_ there is no run time checking of parms.
>
> That's in the C-world.  CPF checks number of parms, and programs that pass
> wrong data types consistently error off.  They don't corrupt data, generally
> speaking.

C (like RPG prototypes) doesn't check prototypes at run time because 
they were already checked at compile time.  If they didn't match, it 
wouldn't compile and you wouldn't be able to run it anyway.  That's one 
reason C (and function/procedure calls) is fast.

Of course, if you screw up the call stack things can get messy...

James Rich

"As for security, being lectured by Microsoft is like receiving wise 
words on the subject of compassion from Stalin."
      -- mormop on lwn.net