Hi. Maybe #parseSourceCode would be better name for #parseTree.
2018-05-02 16:33 GMT+03:00 Marcus Denker <marcus.den...@inria.fr>: > > > > On 27 Apr 2018, at 21:36, Sean P. DeNigris <s...@clipperadams.com> > wrote: > > > > Marcus Denker-4 wrote > >> I will add comments… > > > > I got confused by this again and created an issue: > > https://pharo.manuscript.com/f/cases/21806/Document- > Difference-between-ast-and-parseTree > > > > And then Peter Uhnak reminded me on Discord about this thread. I'm happy > to > > add the comments, but not sure I understand the issue well enough. IIUC > #ast > > is cached, but #parseTree is not. What I don't understand is the purpose > of > > this difference and when one would use one over the other. > > the cached #ast is for one interesting for speed (that is, in situations > where you ask for it often). > > The other use-case is if you want to annotate the AST and keep that > annotation around (till the next > image save, but you can subscribe to ASTCacheReset and re-install the AST > in the cache after cleaning. > (This is used by MetaLinks to make sure they survive image restart). > > The last thing that it provides is that we do have a quite powerful > mapping between bytecode/text/context > and the AST. Regardless how you navigate, you get the same object. > > e.g. even this one works: > > [ 1+2 ] sourceNode == thisContext method ast blockNodes first > > > For example, > > when, if ever, would a user want to access a CM's #ast (as opposed to > > #parseTree) and could modifying it create problems? > > > > Modification is a problem, yes.. code that wants to modify the AST without > making sure the compiledMethod is in sync later > should use #parseTree. > > Code that does not modify the AST (or makes sure to compile it after > modification) is free to use #ast. > or if you want to annotate the AST (which is a modification, after all). > > This is not perfect (not at all…) but the simplest solution to get (to > some extend) what you would have if the system would have > a real persistent, first class AST… > > To be improved. The ASTCache with it’s naive “lets just cache everything > till the next image save” was done with the idea to see > when it would show that it is too naive… for that it worked amazingly well > till now. > > Marcus >
