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As of FPC 2.3.1, the {$MODESWITCH} directive can be used to select some of the features that a {$MODE } directive would select.

It can be used to enable language features that would otherwise not be available in the current mode. For example, you might be programming in TP mode, but want to use the Out parameters, which are only available in Delphi mode.

The {$MODESWITCH } directive enables or disables individual mode features without changing the current compiler mode.

This switch is a global switch, and can be used wherever the {$MODE} switch can be used.

The syntax is as follows:


The first two will switch on feature XXX, the last one will switch it off.

The feature XXX can be one of the following:

Feature Description
ADVANCEDRECORDS allow the use of advanced records (i.e. records with methods)
ALLOWINLINE Allow inline procedures.
ANSISTRINGS Allow use of ansistrings.
AUTODEREF Automatic (silent) dereferencing of typed pointers.
CBLOCKS C style blocks.
CLASSICPROCVARS Use classical procedural variables.
CLASS Use object pascal classes.
CVAR Allow the use of the CVAR keyword.
DEFAULTPARAMETERS Allow use of default parameter values.
DUPLICATELOCALS Allow local variables in class methods to have the same names as properties of the class.
EXCEPTIONS Allow the use of exceptions.
HINTDIRECTIVE Support the hint directives (deprecated, platform etc.)
INITFINAL Allow use of Initialization and Finalization
ISOIO input/output as required by ISO pascal.
ISOMOD mod operation as required by ISO pascal.
ISOPROGRAMPARAS Program parameters as required by ISO pascal.
ISOUNARYMINUS Unary minus as required by ISO pascal.
MACPROCVARS Use mac-style procedural variables.
NESTEDCOMMENTS Allow use of nested comments.
NESTEDPROCVARS Allow assigning local procedures to procedural variables.
NONLOCALGOTO Allow jumping to a location outside the current scope.
OBJECTIVEC1 Allow interfacing with Objective C version 1.
OBJECTIVEC2 Allow interfacing with Objective C version 21.
OBJPAS Automatically include the ObjPas unit.
OUT Allow use of the out parameter type.
PCHARTOSTRING Allow automatic conversion of null-terminated strings to strings,
POINTERTOPROCVAR Allow silent conversion of pointers to procedural variables.
PROPERTIES Allow use of properties.
REPEATFORWARD Implementation and Forward declaration must match completely.
RESULT Enable the Result identifier for function results.
TYPEHELPERS Allow the use of type helpers.
UNICODESTRINGS string is by default unicode string.

Official documentation

See also