1.3.22 $MODESWITCH : Select mode features

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:

{$MODESWITCH XXX}
{$MODESWITCH XXX+}
{$MODESWITCH XXX-}

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

The feature XXX can be one of the following:

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.

SYSTEMCODEPAGE

Set the codepage to the code page of the platform on which the compiler is running. This is automatically enabled if you selected delphiunicode mode: {$mode delphiunicode}.

TYPEHELPERS

Allow the use of type helpers.

UNICODESTRINGS

string is by default unicode string.

Hence, the following:

{$MODE TP}
{$MODESWITCH OUT}

Will switch on the support for the out parameter type in TP mode. It is equivalent to

{$MODE TP}
{$MODESWITCH OUT+}