Re: [Pharo-users] externalizing Magritte descriptions and partial forms

Sept. 21, 2015

      On 21-09-15 02:46, Peter UhnÃ¡k wrote:
...
So far so simple... however what I don't understand:
1. What if I want to have different descriptions for the same attribute?
For example in some views the email is required and in others it is not.
asMagritteMorph is just the quick and dirty variant for straightforward 
situations.
...
2. Must the description be part of the object?
Yes. Single responsibility principle applied.
...
Maybe I am still not fully committed to the having massive protocols
with tons of extension methods instead of externalizing the code to
separate adapters and whatnot.
Ahum, that is exactly what Magritte does, while reusing the smalltalk 
tools. For very large domain models (more than several hundred domain 
classes), you'll be able to do better using a dynamic object model, and 
then you'll have to develop browsers, editors and inspectors for that.
...
3. What if I want only partial rendering?
For example in one view I want to be able to edit only name and age,
and in another one all three.
Since #asMagritteMorph collects everything I don't see how I can customize this.
asMagritteMorph provides the default. On Object it is defined as

Object>>asMagritteMorph
	self magritteDescription  asMorphOn: self

Object>>magritteDescription
	^ self basicMagritteDescription

Object>>basicMagritteDescription
	^ MAPragmaBuilder for: self

which collects all descriptions and puts them in the container described by

Object>descriptionContainer
	"Return the default description container."
	<magritteContainer>
	^ MAPriorityContainer new
		label: self class label;
		yourself.

The nice thing about a MA(Priority)Container is that it supports a
large part of the collection protocol, so you can just do

Person>>asNameMagritteMorph
	^(self magritteDescription select: [:each | each label = 'Name']) 
asMorphOn: self

So you'd  define all possible descriptions you want on the domain object 
itself, possibly using extension methods, and override #asMagritteMorph 
to only return the default descriptions. For complex dependencies with 
extensions, use a smarter MAPragmaBuilder subclass that makes decisions 
based on which extensions are loaded.

You also want to take a look at reference. In the Seaside generation 
that is used like

MAInternalEditorComponent>>buildComponent
	^ self value isNil ifFalse: [
		(self magritteDescription reference asComponentOn: self value)
			setParent: self;
			yourself ]

so that provides an extension point for nested objects. I don't see it 
used in Magritte-Morph
...
Also, is there maintained Magritte-Spec? I've seen something by Sean,
but it's from 2013 with a single-ish commit.
I don't know if it needs more. Nothing changed in the spec interface 
since then, did there?

Stephan

Re: [Pharo-users] externalizing Magritte descriptions and partial forms

Stephan Eggermont