Nullable types

From Lazarus wiki
Jump to navigationJump to search
The printable version is no longer supported and may have rendering errors. Please update your browser bookmarks and please use the default browser print function instead.

English (en) suomi (fi)

Nullable types are types which can have no value (can be unassigned). One such type in Pascal is Pointer type which can have nil value which means that it isn't assigned to any specific address. Same behavior can be implemented using generic types and advanced records with operator overloading.

The Nullable unit is part of FPC since 3.2.2 and its code can be seen in the GitLab repository: nullable.pp.

Then you can define nullable types like:

NullableChar = TNullable<Char>;
NullableInteger = TNullable<Integer>;
NullableString = TNullable<string>;

See also

The standard nullable type in Object Pascal is Variant.

External links