RTMetricNormalizer new
elements: es;
normalizeSize: #numberOfMethods min: 20 max: 50;
normalizeColor: #numberOfVariables.
I now fully understand your question :-)
The terminology of object-orientation says that an “instance" is an “object” or a
“class instance” (these three appellations are rigorously equivalent).
The code above creates an instance of the class RTMetricNormalizer and initializes it.
There are actually two normalizations, one occurring with the message
#normalizeSize:min:max:, and the second one using #normalizeColor:
As you can guess, the first normalization affects the size while the latter affects the
color. The normalization happens in the method invoked by these messages, which are
RTMetricNormalizer>>normalizeSize:min:max: and RTMetricNormalizer>>
normalizeColor:.
The actual normalization happens in some private methods defined on RTMetricNormalizer. If
you are curious, you can have a look at
RTMetricNormalizer>>normalizeColor: metricBlock using: colors using: transformation
min: min max: max
With “sideeffect” I meant in a way:
RTMetricNormalizer new elements: es; …
RTGridLayout new on: es.
Yes, you are absolutely right. The class RTMetricNormalizer, RTGridLayout operate
by doing side effects on the relevant nodes.
You can keep the instance if you wish so, but this is not necessary in this example.
Note that this way of coding is perfectly normal regarding object-oriented design. There
is nothing particular to Roassal or Pharo here.
Tx for explaining, that symbols and blocks both
respond to #value and can be used interchangeably.
Is there a section in Pharo by example explaining it? I have to look more deeply.
Agile Visualization mentions this aspect (as it is crucial in Roassal):
https://dl.dropboxusercontent.com/u/31543901/AgileVisualization/PharoIntrod…
<https://dl.dropboxusercontent.com/u/31543901/AgileVisualization/PharoIntroduction/0102-PharoIntroduction.html>
End of Section 1 mentions the use of symbols
P.S.: It seems intuitive/compelling how to use
Roassal, but after reading PharobyExample, there is an initial gap to understand the
Roassal model (how it works), at least for me.
Yes, I understand your feeling. Roassal is a balance between easiness of writing
code, and expressiveness of the framework. I believe that in any non-trivial framework /
API there is a bit of complexity / magic that appears both fantastic and disturbing.
Cheers,
Alexandre
BR Mike
Am 20.03.2017 2:39 nachm. schrieb "Alexandre Bergel"
<alexandre.bergel(a)me.com <mailto:alexandre.bergel@me.com>>:
Dear Markus,
Agile Vis ebook is superb, copied following
snippet, know hopefully what it's doing, but want to make sure I understand how it
works (in terms of "plain" Pharo):
Thanks for your nice words.
1) @ RTPopup: Class name is enough, but it is
initiated under the hood?
Yes. You can particularize the popup. For example, consider the script:
-=-=-=-=-=-=-=-=-=
v := RTView new.
es := (RTEllipse new color: Color blue) elementsOn: Collection withAllSubclasses.
v addAll: es.
aPopup := RTPopup new
text: [ :aClass |
'Classname = ', aClass name, String cr,
'NbMethod=', aClass numberOfMethods asString, String cr,
'NbVariables=', aClass numberOfVariables asString ].
aPopup borderColor: Color black.
aPopup textColor: Color white.
aPopup backgroundColor: Color black.
es @ aPopup.
RTMetricNormalizer new
elements: es;
normalizeSize: #numberOfMethods min: 20 max: 50;
normalizeColor: #numberOfVariables.
RTGridLayout new on: es.
v
-=-=-=-=-=-=-=-=-=
<Screenshot 2017-03-20 10.26.56.png>
2) RTMetricNormalizer new ...: There is no need
to keep reference to created object? Why? because messages sent to object (like
normalizeSize) have a "sideeffect" on es?
To RTMetricNormalizer, you can provide the Roassal elements or your objects (#(4 5 1 2 3
5) in your example).
What do you mean by side effect? The class RTMetricNormalizer needs some Roassal elements
to operates. Either you provide them directly, as in the example, or you can provide a
view and the objects (in this case, roassal elements are looked up).
The objects needs to answer to the messages indicated as argument to normalizeSize: and
normalizeColor:. In your example it is #yourself (all pharo objects understand this, which
returns the object itself). In the example I have just given, it is #numberOfMethods and
#numberOfVariables, which are understood by Pharo classes (used as objects).
3) RTMetricNormalizer connects to model via
#yourself? Is every symbol or code block. that is sent to RTMetricNormalizer as argument,
executed when finally "sent" to es?
#yourself in your example indicates where to get the number used for the size and color
normalization. In that case, represented objects (numerical values) are taken directly by
the normalizer. But it could be different as in my example. Classes are represented, and a
metric is used to obtain a numerical value.
Let us know if my answer make things clearer now. If no, then keep asking please :-)
Cheers,
Alexandre
BR Mike
v := RTView new.
es := (RTEllipse new color: Color blue) elementsOn: #(4 5 1 2 3 5).
v addAll: es.
es @ RTPopup.
RTMetricNormalizer new
elements: es;
alphaColor;
normalizeSize: #yourself min: 20 max: 50;
normalizeColor: #yourself.
RTHorizontalLineLayout new alignCenter; on: es.
es @ RTLabeled.
v
--
_,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:
Alexandre Bergel
http://www.bergel.eu <http://www.bergel.eu/>
^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;.
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