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context question

 [1/4] from: kpeters::otaksoft::com at: 31-Aug-2007 15:21

Why does Rebol not complain about 'f2text not having a value in 'show-form2???? It forces me to use the context to talk to the layout and the 'change-text function which makes good sense to me. How come it "sees" the "sub-part" 'f2text when it cannot "see" its parent? Would one of the gurus please shed some light on this for me? As always, thanks a lot! Kai rebol[] ;------------------------------------------- show-form2: does [ unview view/new ctx/form2 ; makes good sense ctx/change-text ; makes good sense set-face f2text "GREEN" ; ?????? ] ;------------------------------------------- form1: center-face layout [ btn "Show form 2" [ show-form2 ] ] ;------------------------------------------- ctx: context [ change-text: does [ set-face f2text "BLUE" ] ; form2: center-face layout [ f2text: text "RED" ] ] ;------------------------------------------- view form1 ;---------------- E o S --------------------

 [2/4] from: anton::wilddsl::net::au at: 1-Sep-2007 22:16

Hi Kai, A deeper understanding of CONTEXT is required. CONTEXT just MAKEs an object! When MAKEing an object, the spec block is first scanned for set-words, but only in the top level. Those set-words that were found in the scan are added to the new object. eg: probe context [a: none do [b: none]] Only A is added to the new object because B: is in a sub-block. In your example, when building CTX, only CHANGE-TEXT: and FORM2: were found in the top level, which you can verify: probe first ctx If you want a word added to a context which is only set in a sub-block, then set it to none in the top-level first. eg: context [ f2text: none change-text: ... ... ] And that explains why F2TEXT was available to SHOW-FORM2; F2TEXT was not bound to CTX, so when you set it, it was set global. Anton.

 [3/4] from: kpeters::otaksoft::com at: 1-Sep-2007 8:34

Thanks again, Anton ~ for taking the time to explain. Just what I needed - that part is now understood. Wouldn't it be neat if context had a /deep refinement? Thanks, Kai On Sat, 1 Sep 2007 22:16:40 +1000, Anton Rolls wrote:

 [4/4] from: anton::wilddsl::net::au at: 3-Sep-2007 22:06

No worries. Context /deep; That sort of thing is coming in Rebol 3 (with modules). But it's possible to make your own function which searches deeply for set-words when constructing a new object. eg: context-deep: func [spec][ ; 1 search spec block recursively for set-words and collect them ; 2 create new object containing each found set-word ; 3 DO a copy of the spec, bound to the new object. ; 4 return the object ] Something similar to that. I have probably forgotten if Ladislav or Gabriele has already done something like this. Check Ladislav's site. Anton.