[fpc-pascal] IStreamPersist - how is it used?

[Noel Duffy]

I'm currently looking into ways to write all the objects in my 
application to a stream. I don't expect to have more than one or two 
hundred objects, so a fully-fledged framework like tiOPF seems like 
overkill. I am trying to find out what the RTL offers to solve this kind 
of problem.

I came across the interface IStreamPersist, but the documentation only 
says that "Any class implementing this interface is expected to be able 
to load its state from a stream or write its state to a stream". It does 
not say what classes or code actually calls those methods. 

Delphi has this interface as well, but the documentation for it is no 
clearer. 

I've also seen TPersistent in the documentation, but it's not clear 
whether IStreamPersist is in any way related to it. TPersistent also 
seems a likely candidate for my streaming requirements, but it does seem 
to depend on me putting everything into published properties. 

Lastly, I'm not sure whether this is the right forum for this, but I 
noticed two minor typos on the SaveToStream documentation page at http://
www.freepascal.org/docs-html/rtl/classes/
istreampersist.savetostream.html. 
The first typo is in the Description section where the method is called 
"SaveFromStream" instead of "SaveToStream". Likely a copy-paste snafu. 
The second is the use of "it's" which should be "its". That is, there 
should be no apostrophe between the t and the s. The "it's" thing is also 
on the LoadFromStream page.