Manpages

PERLDL

NAME

SYNOPSIS

        %> perldl
        perldl> $a=sequence(10) # or any other PDL command

DESCRIPTION

e.g.:

   % perldl
   ReadLines enabled
   perldl> $a = rfits "foo.fits"
   BITPIX =  -32  size = 88504 pixels
   Reading  354016 bytes
   BSCALE =  &&  BZERO =

   perldl> imag log($a+400)
   Displaying 299 x 296 image from 4.6939525604248 to 9.67116928100586 ...

Command-line options

-tk

Load Tk when starting the shell (the perl Tk module, which is available from CPAN must be installed). This enables readline event loop processing.

-f file

Loads the file before processing any user input. Any errors during the execution of the file are fatal.

-w

Runs with warning messages (i.e. the normal perl "-w" warnings) turned-on.

-M module

Loads the module before processing any user input. Compare corresponding "perl" switch.

-m module

Unloads the module before processing any user input.

-I directory

Adds directory to the include path. (i.e. the @INC array) Compare corresponding "perl" switch.

Terminating perldl

Shortcuts and aliases

*

The shell aliases "p" to be a convenient short form of "print", e.g.

   perldl> p ones 5,3

   [
    [1 1 1 1 1]
    [1 1 1 1 1]
    [1 1 1 1 1]
   ]

*

"q" and "x" are short-hand for "quit".

*

"l" lists the history buffer

  perldl> l # list last 20 commands

  perldl> l 40 # list last 40 commands

*

"?" is an alias for help

  perldl> ? wpic

*

"??" is an alias for apropos

  perldl> ?? PDL::Doc

*

help, apropos, usage and sig: all words after these commands are used verbatim and not evaluated by perl. So you can write, e.g.,

    help help

instead of

    help 'help'

The startup file ~/.perldlrc

To set even more local defaults the file local.perldlrc (in the current directory) is sourced if found. This lets you load modules and define subroutines for the project in the current directory.

The name is chosen specfically because it was found hidden files were NOT wanted in this circumstances.  

Shell variables

*

$PERLDL::ESCAPE - default value '#'

Any line starting with this character is treated as a shell escape. The default value is chosen because it escapes the code from the standard perl interpreter.

*

$PERLDL::PAGER - default value "more"

External program to filter the output of commands. Using "more" prints output one screenful at a time. On Unix, setting page(1) and $PERLDL::PAGER to "tee -a outfile" will keep a record of the output generated by subsequent perldl commands (without paging).

*

$PERLDL::PROMPT - default value 'perldl> '

Enough said But can also be set to a subroutine reference, e.g. $PERLDL::PROMPT = sub {join(':',(gmtime)[2,1,0]).'> '} puts the current time into the prompt.

*

$HOME

The user's home directory

*

$PERLDL::TERM

This is the Term::ReadLine object associated with the perldl shell. This can be used by routines called from perldl if your command is interactive.

Executing scripts from the perldl prompt

      perldl> # emacs script &
                      -- add perldl code to script and save the file
      perldl> do 'script'

Running ``do 'script''' again updates any variables and function definitions from the current version of 'script'.  

Automatically execute your own hooks

A simple example would be to print the time of each command:

 perldl> push @PERLDL::AUTO,'print scalar(gmtime),"\n"'

 perldl> print zeroes(3,3)
 Sun May  3 04:49:05 1998

 [
  [0 0 0]
  [0 0 0]
  [0 0 0]
 ]

 perldl> print "Boo"
 Sun May  3 04:49:18 1998
 Boo
 perldl>

 perldl> push @PERLDL::AUTO,"do 'local.perldlrc'"

Another example application is as a hook for Autoloaders (e.g. PDL::AutoLoader) to add code too which allows them to automatically re-scan their files for changes. This is extremely convenient at the interactive command line. Since this hook is only in the shell it imposes no inefficiency on PDL scripts.

Finally note this is a very powerful facility - which means it should be used with caution!  

Command preprocessing

In some cases, it is convenient to process commands before they are sent to perl for execution. For example, this is the case where the shell is being presented to people unfamiliar with perl but who wish to take advantage of commands added locally (eg by automatically quoting arguments to certain commands).

The variable $PERLDL::PREPROCESS can be set to a code reference (usually in a local configuration file) that will be called, with the current string as argument, just prior to the string being executed by the shell. The modified string should be returned.

The following code would check for a call to function 'mysub' and bracket arguments with qw.

 $PERLDL::PREPROCESS = sub {
   my $str = shift;
   $str =~ s/^\s+//;  # Strip leading space
   if ($str =~ /^mysub/) {
     my ($command, $arguments) = split(/\s+/,$str, 2);
     $str = "$command qw( $arguments )" 
       if (defined $arguments && $arguments !~ /^qw/);
   };
   # Return the input string, modified as required
   return $str;
 };

  perldl> mysub arg1 arg2

  perldl> mysub qw( arg1 arg2 )

perldl and PDL::NiceSlice

At startup "perldl" will let you know if niceslicing is enabled. The startup message will contain info to this end, something like this:

   perlDL shell v1.XX
    PDL comes with ABSOLUTELY NO WARRANTY. For details, see the file
    'COPYING' in the PDL distribution. This is free software and you
    are welcome to redistribute it under certain conditions, see
    the same file for details.
   ReadLines, NiceSlice  enabled
   Reading /home/csoelle/.perldlrc...
   Type 'demo' for online demos
   Loaded PDL v2.XX

  perldl> $a = sequence 10;
  perldl> p $a(3:8:2)

PDL::NiceSlice installs a filter in the
 $PERLDL::PREPROCESS variable (see above) to enable the enhanced slicing syntax. You can use a few commands in the "perldl" shell to switch this preprocessing on or off and also explicitly check the substitutions that the NiceSlice filter makes.

You can switch the PDL::NiceSlice filter on and off by typing

  perldl> trans # switch niceslicing on

  perldl> notrans # switch niceslicing off

To see how your commands are translated switch reporting on:

  perldl> report 1;
  perldl> p $a(3:8:2)
 processed p $a->nslice([3,8,2])
 [3 5 7]

  perldl> report 0;
  perldl>  p $a(3:8:2)
 [3 5 7]

Index

NAME

SYNOPSIS

DESCRIPTION

Command-line options

Terminating perldl

Shortcuts and aliases

The startup file ~/.perldlrc

Shell variables

Executing scripts from the perldl prompt

Automatically execute your own hooks

Command preprocessing

perldl and PDL::NiceSlice