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Top Forums Shell Programming and Scripting Multiple co-processor file descriptors Post 64819 by tmarikle on Wednesday 2nd of March 2005 01:38:16 PM
Old 03-02-2005
Sorry, again, I am not trying to bump anything up, I have a core issue, that I am trying to narrow this thread's scope to focus on, using "eval" that is eluding me so if I can get past this, my problem is solved.

Essentially my "x" variable should be able to translate into another variable containing my file descriptor. If I can get "x" to expand into TEXTVAR2_stdout and then expand this so that "4" can be assigned to a local function variable, I am golden.

Code:
#!/usr/bin/ksh

sqlplus -s /nolog |&

x=TESTVAR2

eval export "${x}_stdout=3"
eval export "${x}_stdin=4"

# Print using named variables
print $TESTVAR2_stdout
print $TESTVAR2_stdin

# Same thing attempting expansion of my "x" variable;
# results in print TESTVAR2_stdout but no 4
eval "print ${x}_stdout"
# results in print $TESTVAR2_stdout
print $(expr $"${x}_stdout")

I get down to something that looks like $TESTVAR2_stdout but I cannot get the shell to treat it as a variable.

Thomas
 

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Perl::Critic::Policy::BuiltinFunctions::ProhibitStringyEUser3Contributed Perl DocumePerl::Critic::Policy::BuiltinFunctions::ProhibitStringyEval(3)

NAME
Perl::Critic::Policy::BuiltinFunctions::ProhibitStringyEval - Write "eval { my $foo; bar($foo) }" instead of "eval "my $foo; bar($foo);"". AFFILIATION
This Policy is part of the core Perl::Critic distribution. DESCRIPTION
The string form of "eval" is recompiled every time it is executed, whereas the block form is only compiled once. Also, the string form doesn't give compile-time warnings. eval "print $foo"; # not ok eval {print $foo}; # ok CONFIGURATION
There is an "allow_includes" boolean option for this Policy. If set, then strings that look like they only include a single "use" or "require" statement (with the possible following statement that consists of a single number) are allowed. With this option set, the following are flagged as indicated: eval 'use Foo'; # ok eval 'require Foo'; # ok eval "use $thingy;"; # ok eval "require $thingy;"; # ok eval "use $thingy; 1;"; # ok eval "require $thingy; 1;"; # ok eval 'use Foo; blah;'; # still not ok eval 'require Foo; 2; 1;'; # still not ok eval 'use $thingy;'; # still not ok eval 'no Foo'; # still not ok If you don't understand why the number is allowed, see Perl::Critic::Policy::ErrorHandling::RequireCheckingReturnValueOfEval. This option inspired by Ricardo SIGNES' Perl::Critic::Policy::Lax::ProhibitStringyEval::ExceptForRequire. SEE ALSO
Perl::Critic::Policy::ControlStrucutres::RequireBlockGrep Perl::Critic::Policy::ControlStrucutres::RequireBlockMap AUTHOR
Jeffrey Ryan Thalhammer <jeff@imaginative-software.com> COPYRIGHT
Copyright (c) 2005-2011 Imaginative Software Systems. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. The full text of this license can be found in the LICENSE file included with this module. perl v5.16.3 2014-06-09 Perl::Critic::Policy::BuiltinFunctions::ProhibitStringyEval(3)
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