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Calling a function through a variable

 
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# 1  
Old 09-29-2009
Calling a function through a variable
Hey folks,

I'm pretty new to unix programming. I was trying to get something to work but it's not doing what I expected.

Code:
 
#!/bin/ksh
 
. ./functions.sh
 
STRING=function_1
FUNCTION="$STRING"
RETURN=eval $FUNCTION
echo "value of $FUNCTION function is: $RETURN"

All i'm trying to do is evalute function_1 and use the function's name and return value in an echo statement.

With the above, the 'RETURN=eval $FUNCTION' echos the evaluated function to the screen. While $RETURN is returning nothing.

Any idea what i'm doing wrong?

The reason i'm doing things this way is that I want to eventually stick this is a loop and have this run for all functions that i chose to call (in a seperate file)... but baby steps and all that.

TIA

Daithí
# 2  
Old 09-29-2009
You are getting the null out put and you must me from this code, because you are just trying to get the value stored in "$FUNCTION" which is nothing the undefined variable(function_1).

By the way , are you getting any error like "function_1 command not found"


Regards,
Sanjay
# 3  
Old 09-29-2009
Maybe this is what you are looking for:

Code:
$> cat lib
somefunk()
{
 echo somestring
 return 7
}
$> cat mach.sh
. ./lib

echo `eval somefunk` $?
$> ./mach.sh
somestring 7

# 4  
Old 09-29-2009
I'm not getting the "function_1 command not found" error anymore. I was getting something similar to that when trying to run the functions.sh script using './functions.sh' instead of '. ./functions.sh' but have no idea why that was.

let's say i have function_1 is instead the following:
Code:
now()
{
    date +%Y%m%d%H%M%S
}

so when i run test.sh
Code:
. ./functions.sh
###################################################
RETURN=""
FUNCTION=""
STRING=""
####################################################
echo
STRING=now
FUNCTION="$STRING"
RETURN=eval $FUNCTION
echo "value of $FUNCTION function is: $RETURN"
echo

i get the following
Code:
20090929100109
value of now function is:

what i want to see is
Code:
value of now function is: 20090929100109

I suppose what i'm asking is can i evaluate a function and assign that return value to a variable?
# 5  
Old 09-29-2009
Am I missing something?

Code:
bash -c '
  now() { 
    date +%Y%m%d%H%M%S
    }
  STRING=now FUNCTION=$STRING
  RETURN="$($FUNCTION)"
  printf "return is: %s\n" "$RETURN"
  '

outputs:
Code:
zsh-4.3.10[sysadmin]% bash -c '
  now() {
    date +%Y%m%d%H%M%S
}
  STRING=now FUNCTION=$STRING
  RETURN="$($FUNCTION)"
  printf "return is: %s\n" "$RETURN"
  '
return is: 20090929111720

This should work with ksh, bash and zsh.
# 6  
Old 09-29-2009
Thanks radoulov. That worked perfectly.

Code:
RETURN="$($FUNCTION)"

this was all i needed. my unix is very rusty. better dust off the training manuals again.
 
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