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Top Forums Shell Programming and Scripting Blog-Thread: Creating a Shell Wrapper and Runtime Modifier (SWARM) Post 303045307 by drl on Monday 16th of March 2020 07:10:46 AM
Old 03-16-2020
Hi.

Perhaps I missed something, but variables are created/set when from a function:
Code:
#!/usr/bin/env bash

# @(#) s1       Demonstrate use of option "-g" in "declare".

LC_ALL=C ; LANG=C ; export LC_ALL LANG
pe() { for _i;do printf "%s" "$_i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }
em() { pe "$*" >&2 ; }
db() { ( printf " db, ";for _i;do printf "%s" "$_i";done;printf "\n" ) >&2 ; }
db() { : ; }
C=$HOME/bin/context && [ -f $C ] && $C

(
        declare -g my_test_a="a test"
        export my_test_b="an exported beer"
)

unset my_test_a my_test_b
pl " Results, not in function:"
echo $my_test_a
echo $my_test_b

f1 ()
{
    declare -g my_test_a="a test"
    export my_test_b="an exported beer"
}

unset my_test_a my_test_b
pl " Results, in function f1:"
f1
echo $my_test_a
echo $my_test_b

exit

producing:
Code:
$ ./s1

Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 3.16.0-7-amd64, x86_64
Distribution        : Debian 8.11 (jessie) 
bash GNU bash 4.3.30

-----
 Results, not in function:



-----
 Results, in function f1:
a test
an exported beer

Seen in man bash:
Quote:
-g create global variables when used in a shell function; otherwise
ignored
and noted with shellcheck:
Code:
...
In s1 line 21:
echo $my_test_a
     ^-- SC2031: my_test_a was modified in a subshell. That change might be lost. 
...

Apologies if I missed it ... cheers, drl

( currently listening: Bartok: String Quartets, but soon Yes )
This User Gave Thanks to drl For This Post:
 
Test Your Knowledge in Computers #953
Difficulty: Medium
A memory-resident virus installs itself as part of the operating system when executed, after which it remains in RAM from the time the computer is booted up to when it is shut down.
True or False?

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Alzabo::Runtime::UniqueRowCache(3pm)			User Contributed Perl Documentation		      Alzabo::Runtime::UniqueRowCache(3pm)

NAME
Alzabo::Runtime::UniqueRowCache - Implements a row cache for Alzabo SYNOPSIS
use Alzabo::Runtime::UniqueRowCache; Alzabo::Runtime::UniqueRowCache->clear(); DESCRIPTION
This is a very simple caching mechanism for "Alzabo::Runtime::Row" objects that tries to ensure that for there is never more than one row object in memory for a given database row. To use it, simply load it. It can be foiled through the use of "Storable" or other "deep magic" cloning code, like in the "Clone" module. The cache is a simple hash kept in memory. If you use this module, you are responsible for clearing the cache as needed. The only time it is cleared automatically is when a table update or delete is performed, in which case all cached rows for that table are cleared. In a persistent environment like mod_perl, you should clear the cache on a regular basis in order to prevent the cache from getting out of sync with the database. A good way to do this is to clear it at the start of every request. METHODS
All methods provided are class methods. * clear This clears the entire cache * clear_table( $table_object ) Given a table object, this method clears all the cached rows from that table. * row_in_cache( $table_name, $row_id ) Given a table name and a row id, as returned by the "Alzabo::Runtime::Row->id_as_string" method, this method returns the matching row from the cache, if it exists. Otherwise it returns undef. * delete_from_cache( $table_name, $row_id ) Given a table name and a row id, as returned by the "Alzabo::Runtime::Row->id_as_string" method, this method returns the matching row from the cache. * write_to_cache( $row_object ) Given a row object, this method stores it in the cache. AVOIDING THE CACHE
If you want to not cache a row, then you can pass the "no_cache" parameter to any table or schema method that creates a new row object or a cursor, such as "Alzabo::Runtime::Table->insert()", "Alzabo::Runtime::Table->rows_where()". AUTHOR
Dave Rolsky, <autarch@urth.org> perl v5.8.8 2007-12-23 Alzabo::Runtime::UniqueRowCache(3pm)

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