[fpc-devel] Differences between 'tsym' and 'tdef'

[Paul Ishenin]

18.05.12 5:32, Joost van der Sluis wrote:

> Now I'm wondering if I should make this new field of Tpropertysym a TDef
> or a TSym(table). I know that Tsym can store itself to a ppu while a
> TDef does not. But There was something else, too. But I don't remember
> exactly.

TSym is about symbol and TDef is about definition. Each symbol is just 
an identifier which compiler founds during parse which may have > 1 
definitions (overloaded functions for example). A definition does not 
have a name (generally) but instead have information how to work with 
it. It may refer to no symbol at all. Both are stored in a TSymTable and 
ppu (look at TStoredDef).

A property does not have a definition of itself - only a symbol and list 
of fields/procedures for read,write,stored.

> So two questions: how should I extend the Tpropertysym for the extended
> attributes, and what is the dfference/use of Tdef and Tsym.

Does any symbol in delphi may have this information? If property has 
this information and you created a descendant property - will it have 
the same attributes as an ancestor property?

For now if only property may have this information then choose 
TPropertySym for storing it.

Best regards,
Paul Ishenin