[Newbies] Answering a question: Are messages objects? Running into a problem with sendTo:

Tobias Pape Das.Linux at gmx.de
Sat Dec 28 09:27:24 UTC 2019

> On 28.12.2019, at 05:09, Mark Miller <mmille10 at comcast.net> wrote:
> 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).

The difference is the missing colon in the message.


	(Message selector: #sendTo: argument: '5') sendTo: (Message selector: #asInteger)
instead of 
	(Message selector: #sendTo argument: '5') sendTo: (Message selector: #asInteger)

Best regards
> 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 at comcast.net

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