I was trying to explain in a question on Smalltalk (on Quora.com) how messages are also objects, and I'm running into a bit of a problem in trying to demonstrate this in either Squeak or Pharo.
I started off using a simple example:
'5' asInteger --> 5
I can do the same thing with:
(Message selector: #asInteger) sendTo: '5' --> 5
This all works fine.
The response I got back from the person I was trying to convince was that since I'm using syntax to create and send a message (using sendTo: with a Message class), it's not really a message, because if a constructed message with Message is a message, then why use syntax to send "sendTo:" to it? He contends it's an object being used to represent a message. The actual message gets sent in the process of evaluation (I suppose he thinks the message is "unwrapped" from Message, and is sent under the covers).
I was going to try the following, to perhaps be more convincing (though I don't know if this is a lost cause re. convincing), but I ran into a problem. I tried translating the 2nd expression above into more explicit terms, and I'm running into an exception I can't explain. To me, what I'm doing is equivalent to the 2nd expression, but Smalltalk disagrees.
First version:
| m1 m2 | m1 := Message selector: #asInteger. m2 := Message selector: #sendTo argument: '5'. m2 sendTo: m1.
I also tried the following:
(Message selector: #sendTo argument: '5') sendTo: (Message selector: #asInteger)
In both cases, in both Squeak and Pharo, it throws up an exception saying:
"Message(Object)>>doesNotUnderstand: #sendTo" (Squeak)
or
"Instance of Message did not understand #sendTo" (Pharo).
This is bizarre to me, because if I look at Message in a browser, I can clearly see sendTo: is an instance method. Also, if it wasn't an instance method, then my very first example wouldn't have worked. I suspect I'm running into some underlying mechanics of how messages are sent, and how object state works in expressions.
Is this a bug? Am I missing something in how I'm using sendTo:? Or, does my experimentation reveal that I'm wrong about messages? :)
Thanks in advance for any clarity on this.
---Mark mmille10@comcast.net
-- Sent from: http://forum.world.st/Squeak-Beginners-f107673.html