Opcode - Disable named opcodes when compiling perl code
use Opcode;Perl code is always compiled into an internal format before execution.
Evaluating perl code (e.g. via "eval" or "do 'file'") causes the code to be compiled into an internal format and then, provided there was no error in the compilation, executed. The internal format is based on many distinct opcodes.
By default no opmask is in effect and any code can be compiled.
The Opcode module allow you to define an operator mask to be in effect when perl next compiles any code. Attempting to compile code which contains a masked opcode will cause the compilation to fail with an error. The code will not be executed.
The Opcode module is not usually used directly. See the ops pragma and Safe modules for more typical uses.
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Your mileage will vary. If in any doubt do not use it.
The canonical list of operator names is the contents of the array PL_op_name defined and initialised in file opcode.h of the Perl source distribution (and installed into the perl library).
Each operator has both a terse name (its opname) and a more verbose or recognisable descriptive name. The opdesc function can be used to return a list of descriptions for a list of operators.
Many of the functions and methods listed below take a list of operators as parameters. Most operator lists can be made up of several types of element. Each element can be one of
Operator names are typically small lowercase words like enterloop, leaveloop, last, next, redo etc. Sometimes they are rather cryptic like gv2cv, i_ncmp and ftsvtx.
Operator tags can be used to refer to groups (or sets) of operators. Tag names always begin with a colon. The Opcode module defines several optags and the user can define others using the define_optag function.
An opname or optag can be prefixed with an exclamation mark, e.g., !mkdir. Negating an opname or optag means remove the corresponding ops from the accumulated set of ops at that point.
An opset as a binary string of approximately 44 bytes which holds a set or zero or more operators.
The opset and opset_to_ops functions can be used to convert from a list of operators to an opset and vice versa.
Wherever a list of operators can be given you can use one or more opsets. See also Manipulating Opsets below.
The Opcode package contains functions for manipulating operator names tags and sets. All are available for export by the package.
In a scalar context opcodes returns the number of opcodes in this version of perl (around 350 for perl-5.7.0).
In a list context it returns a list of all the operator names. (Not yet implemented, use @names = opset_to_ops(full_opset).)
Returns an opset containing the listed operators.
Returns a list of operator names corresponding to those operators in the set.
Returns a string representation of an opset. Can be handy for debugging.
Returns an opset which includes all operators.
Returns an opset which contains no operators.
Returns an opset which is the inverse set of the one supplied.
Returns true if the supplied opset looks like a valid opset (is the right length etc) otherwise it returns false. If an optional second parameter is true then verify_opset will croak on an invalid opset instead of returning false.
Most of the other Opcode functions call verify_opset automatically and will croak if given an invalid opset.
Define OPTAG as a symbolic name for OPSET. Optag names always start with a colon :.
The optag name used must not be defined already (define_optag will croak if it is already defined). Optag names are global to the perl process and optag definitions cannot be altered or deleted once defined.
It is strongly recommended that applications using Opcode should use a leading capital letter on their tag names since lowercase names are reserved for use by the Opcode module. If using Opcode within a module you should prefix your tags names with the name of your module to ensure uniqueness and thus avoid clashes with other modules.
Adds the supplied opset to the current opmask. Note that there is currently no mechanism for unmasking ops once they have been masked. This is intentional.
Returns an opset corresponding to the current opmask.
This takes a list of operator names and returns the corresponding list of operator descriptions.
Dumps to STDOUT a two column list of op names and op descriptions. If an optional pattern is given then only lines which match the (case insensitive) pattern will be output.
It's designed to be used as a handy command line utility:
perl -MOpcode=opdump -e opdump
perl -MOpcode=opdump -e 'opdump Eval'