Routines (by topic) > Programming and IDL Control

# Programming and IDL Control

!NULL - A variable of type Undefined.

APP_USER_DIR - Provides access to the application user directory.

APP_USER_DIR_QUERY - Locates existing application user directories.

ARG_PRESENT - Returns TRUE if the value of the specified variable can be passed back to the caller.

BREAKPOINT - Sets and clears breakpoints for debugging.

BYTEORDER - Converts between host and network byte ordering.

CALL_FUNCTION - Calls a function given the function's name as a string.

CALL_METHOD - Calls an IDL object method.

CALL_PROCEDURE - Calls a procedure given the procedure's name as a string.

CATCH - Declares and clears exception handlers.

CODE_COVERAGE - Return line numbers of executed and un-executed code within a routine.

COMMAND_LINE_ARGS - Returns string values supplied when the user starts IDL with the -arg or -args command line options.

CPU - Changes the values stored in the read-only !CPU system variable.

CREATE_STRUCT - Creates and concatenates structures.

COMPILE_OPT - Change default rules for compiling routines.

DEFINE_KEY - Programs keyboard function keys.

DEFINE_MSGBLK - Defines and loads a new message block into the current IDL session.

DEFINE_MSGBLK_FROM_FILE - Reads the definition of a message block from a file, and loads it into the current IDL session.

DEFSYSV - Creates a new system variable.

EXECUTE - Compiles and executes IDL statements contained in a string.

EXIT - Quits IDL and exits back to the operating system.

EXPAND_PATH - Expands path-definition string into full path name for use with the !PATH system variable.

HEAP_FREE - Recursively frees all heap variables referenced by its input argument.

HEAP_GC - Performs garbage collection on heap variables.

HEAP_NOSAVE - Used to clear the save attribute of pointer or object heap variables.

HEAP_REFCOUNT - Returns the current reference count for a pointer or object reference.

HEAP_SAVE - Used to query whether a pointer or object heap variable is savable. It can also be used to change the heap variable save attribute.

IDL_VALIDNAME - Determines whether a string may be used as a valid IDL variable name or structure tag name.

KEYWORD_SET - Returns True if given expression is defined and nonzero or an array.

LAMBDA - Create inline Lambda functions.

LAMBDAP - Create inline Lambda procedures.

LMGR - Determines the type of license used by the current IDL session.

LOGICAL_AND - Performs a logical AND operation on its arguments.

LOGICAL_OR - Performs a logical OR operation on its arguments.

LOGICAL_TRUE - Determines whether its arguments are non-zero (or non-NULL).

MEMORY - Provides information about the amount of dynamic memory currently in use by the IDL session.

MESSAGE - Issues error and informational messages.

N_ELEMENTS - Returns the number of elements contained in an expression or variable.

N_PARAMS - Returns the number of non-keyword parameters used in calling a procedure or function.

N_TAGS - Returns the number of tags in a structure.

OBJ_CLASS - Determines the class name of an object.

OBJ_DESTROY - Destroys an object reference.

OBJ_HASMETHOD - Determines whether an object class implements or inherits a specified method or methods.

OBJ_ISA - Determines inheritance relationship of an object.

OBJ_NEW - Creates an object reference.

OBJ_VALID - Verifies validity of object references.

ON_ERROR - Designates the error recovery method.

ON_IOERROR - Declares I/O error exception handler.

PATH_CACHE - Controls IDL’s path caching mechanism.

PREF_COMMIT - Commits IDL preferences in the pending state.

PREF_GET - Returns information about IDL preferences.

PREF_SET - Sets new values for IDL preferences.

PROFILER -Analyze the performance of IDL code applications.

PTR_FREE - Destroys a pointer.

PTR_NEW - Creates a pointer.

PTR_VALID - Verifies the validity of pointers.

PTRARR - Creates an array of pointers.

RECALL_COMMANDS - Returns entries in IDL’s command recall buffer.

RESOLVE_ALL - Compiles any uncompiled routines.

RESOLVE_ROUTINE - Compiles a routine.

RETALL - Returns control to the main program level.

RETURN - Returns control to the next-higher program level.

ROUTINE_INFO - Provides information about compiled procedures and functions.

STOP - Stops the execution of a running program or batch file.

STRMESSAGE - Returns the text of a given error number.

STRUCT_ASSIGN - Uses relaxed-structure assignment to copy structures.

STRUCT_HIDE - Prevents the IDL HELP procedure from displaying information about structures or objects.

SWAP_ENDIAN - Reverses the byte ordering of scalars, arrays or structures.

SWAP_ENDIAN_INPLACE - Reverses the byte ordering of scalars, arrays or structures, without making a copy.

TAG_NAMES - Returns the names of tags in a structure.

TEMPORARY - Returns a temporary copy of a variable, and sets the original variable to Undefined.

WAIT - Suspends execution of the program for a specified period.