Calling perl built-in functions

[Janek Schleicher]

Jon wrote at Tue, 02 Sep 2003 04:12:37 -0700:

my $function = "print";
my $args = "hello, world";

&$function $args;


It produces:
Undefined subroutine &main:rint called

Is there a way to make this work?

Well, you can always do the eval workaround:

eval "$function $args";

with some more problems ...

But what's the problem behind the problem you've written to us?


Greetings,
Janek

 

[Jon]

I have a script that parses a file. In this file, I would like to be able to
put in perl build in functions. So, with that in mind, let me give you this
example that doesn't work:

my $function = "print";
my $args = "hello, world";

&$function $args;


It produces:
Undefined subroutine &main:rint called

Is there a way to make this work?

Thanks in advance,

Jon

 

[Anno Siegel]

I have a script that parses a file. In this file, I would like to be able to
put in perl build in functions. So, with that in mind, let me give you this
example that doesn't work:

my $function = "print";
my $args = "hello, world";

&$function $args;


It produces:
Undefined subroutine &main:rint called

Well, builtins are not subroutines and can't be called as such.

Is there a way to make this work?

Make it work how? Do you want to change $function and $args so that
"&$function $args" works, or do you want to keep the values in $function
and $args and write a call that works?

Both are possible. Make up your mind.

Anno

 

[Shawn Corey]

Well, builtins are not subroutines and can't be called as such.




Make it work how? Do you want to change $function and $args so that
"&$function $args" works, or do you want to keep the values in $function
and $args and write a call that works?

Both are possible. Make up your mind.

Anno

From my bag of dirty tricks:
#!/usr/bin/perl

$function='print';

&$function("Hello, world\n");

sub print {
print @_;
}

 

[Uri Guttman]

SC> From my bag of dirty tricks:

very dirty.

SC> #!/usr/bin/perl

SC> $function='print';

SC> &$function("Hello, world\n");

SC> sub print {
SC> print @_;
SC> }

try that under use strict.

next!!

uri

 

[Shawn Corey]

SC> From my bag of dirty tricks:

very dirty.

SC> #!/usr/bin/perl

SC> $function='print';

SC> &$function("Hello, world\n");

SC> sub print {
SC> print @_;
SC> }

try that under use strict.

next!!

uri

I didn't say it was good programming pratice; in fact, I called it a
dirty trick.

 

[Jon]

Sorry for the delayed response...I ended up going out of town and just
got back.

Here is the problem I'm having. Using Parse::RecDescent, I wrote a
simple language for my users to run tests without having to know Perl.
For, example, a config file would look like:

parallel {
test1
test2
test3
}

serial {
test1
test2
test3
}

This then does all the perl stuff like forking to run tests in
parallel or serial without the user not having to know anything other
than my simple language. Here is something I would like to add:

serial {
test1
print(running test2)
test2
}

Here's the kicker though...I want them to use any perl built in
function without me having to know ahead of time. I don't want to
have a function called print that runs the built-in print function
when it sees it in my file. I would like to parse the file and get
back $function($args) and then run it. $function can be any built in
function, but I won't know what it is.

Does that make sense?

Thanks