pget

Context: paramio

Synopsis

Get a parameter value as a string.

Syntax

pget(paramfile, paramname)

Description

This function is essentially the same as the command-line version (see "ahelp tools pget"), although only one parameter can be accessed at a time.

The parameter value is always returned as a string by this function; the paramio library does contain functions - such as pgetb() and pgetd() - which will automatically convert the value into the requested datatype. The pquery() function may also be of interest.

The paramio module is not available by default; see "ahelp paramio" for information on loading the module.

Examples

Example 1

>>> punlearn("dmcopy")
>>> ifile = pget("dmcopy", "infile")
>>> clval = pget("dmcopy", "clobber")
>>> if ifile == "": print("infile is empty!")

infile is empty!
>>> print(clval)
no

Here we use pget() to find the current settings of the "infile" and "clobber" parameters of the "dmcopy" parameter file. Note that clval contains a string and not a boolean value; the pgetb() routine could have been used here instead.

Example 2

>>> punlearn("dmcopy")
>>> fp = paramopen("dmcopy")
>>> ifile = pget(fp, "infile")
Input dataset/block specification (): in.fits
>>> clval = pget(fp, "clobber")
>>> paramclose(fp)
>>> print(ifile)
in.fits
>>> print(clval)
no

This example is similar to the first except that we use the return value of paramopen() to access the parameter file. If you make many paramio calls on a single parameter file then it is more efficient to use paramopen() than just using the name of the parameter file.

Since we did not supply a mode parameter for the paramopen() call, it defaults to "r" and so the paramater was prompted for when pget() was called.

Example 3

>>> punlearn("dmcopy")
>>> fp = paramopen("dmcopy", "rH")
>>> ifile = pget(fp, "infile")
>>> paramclose(fp)
>>> if ifile == "": print("infile is empty!")

infile is empty!

By opening the parameter file with the mode set to "rH" we avoid the interactive prompt when pget() is called.