Pragmatic directives: Difference between revisions

Line 299:

=={{header|PicoLisp}}==

PicoLisp makes no formal difference between any normal and "specific" operation of the language. Any possible desired effect can be achieved by calling a function or setting a variable. For example, function calls can be traced with the '[http://software-lab.de/doc/refT.html#trace trace]' function.

/* {{header|PL/I}} */ Section added -- Superfluous blanks suppressed

=={{header|PL/I}}==

Disabled on-conditions can be seen as pragmatic directives.

SubscriptRange (SUBRG), StringRange (STRG), StringSize (STRZ), Size conditions

can be enabled for a PROCEDURE or a BEGIN block.

By default, for optimization reasons,

SubscriptRange,StringRange,StringSize,Size are disabled.

If enabled the SubscriptRange condition is raised for out-of-bound subscript of

an array.

For example:

declare (t(100),i) fixed binary;

i=101;

t(i)=0;

</lang>

will cause unpredictible results.

And :

</lang>

(SubscriptRange): begin;

declare (t(100),i) fixed binary;

i=101;

t(i)=0;

end;

</lang>

will issue the message : "The SubscriptRange condition was raised." at execution time.

Or, it can be handle by an on-unit.

(SubscriptRange): begin;

declare (t(100),i) fixed binary;

i=101;

on SubscriptRange begin; put skip list('error on t(i)'); goto e; end;

t(i)=0;

e:on SubscriptRange system; /* default dehaviour */

end;

</lang>

And the same way for a string,

the StringRange condition is raised when a substring reference is beyond

the span of the string.

And finally.

The StringSize condition is raised when a string is shorten

as a result of a convertion assigment.

The Size condition is raised when a numerical value is shorten

as a result of a convertion assigment.

=={{header|Python}}==