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Re: [Pharo-dev] new pharo cheatsheet

by stepharo

Yes I should/may update it Le 8/4/16 22:03, Cyril Ferlicot Delbecque a Ã©crit : > > On 08/04/2016 21:56, stepharo wrote: >> new cheatsheet for Pharo syntax. >> Any feedback is welcome > Hi, > > The screen seems to be from Pharo 1 no? > >> Stef

April 9, 2016

Proportional Layout does not work for me

by kmo

I was just experimenting with creating a user interface in Pharo using Morphic. I wanted to create a sub-morph that fills its parent with a 50 pixel gap at the top and a 50 pixel gap at the bottom (leaving space for a toolbar at the top and a status bar at the bottom). This code works in pharo 3 but does not work in pharo 4 or 5: Morph>>>initialize |frame sub| super initialize. self layoutPolicy: ProportionalLayout new. frame := LayoutFrame fractions: (0.0 @ 0.0 corner: 1.0@ 1.0) offsets: (0@50 corner: 0@50 negated). sub := BorderedMorph new. sub color: Color red. self addMorph: sub fullFrame: frame. self extent:600@600. Am I doing something wrong or is proportional layout broken? -- View this message in context: http://forum.world.st/Proportional-Layout-does-not-work-for-me-tp4889237.ht… Sent from the Pharo Smalltalk Developers mailing list archive at Nabble.com.

April 9, 2016

Re: [Pharo-dev] new pharo cheatsheet

by Ben Coman

On Sat, Apr 9, 2016 at 3:52 PM, olivier auverlot <olivier.auverlot(a)gmail.com> wrote: > I think that it could be interesting to use it also on a simple HTML page > for the Pharo web site. This document can be put in the main menu > ("Beginners" ?) just before "Documentation". > > It's really cool to have a synthesis document for the newcomers. I came across this a while ago and found it quite interesting... http://www2.ing.unipi.it/~a009435/issw/extra/readingSmalltalk.pdf

April 9, 2016

Re: [Pharo-dev] new pharo cheatsheet

by Ben Coman

On Sat, Apr 9, 2016 at 3:56 AM, stepharo <stepharo(a)free.fr> wrote: > new cheatsheet for Pharo syntax. > Any feedback is welcome So I really went to town and picked the eyes out of it... > #(abc 123) > literal array with the symbol #abc and the number 123 This one surprised me. I had to test it to check it was true. It doesn't seem very consistent. Regardless of whether we *can* do it like that, it would be more intuitive to be #(123 #abc). But really, should we even allow it? > 12 2r1100 16rC > twelve (decimal, binary, hexadecimal) floating-point numbers The correspondence of the '2' of the '12 very close to the '2' of the '2r' is a bit awkward. Also I think we can take decimal numbers for granted and its easier for people to immediately identify A=10 rather than C=12, and lets not leave the meaning of 'r' implicit. So perhaps use.... 2r1010 16rA binary and hexadecimal radix of 10 > {foo . 3 + 2} Perhaps move the "declaration of two temporary variables" above this, so foo it properly introduce foo as a variable rather than leaving it implicit. Otherwise from the literal array example it might be inferred that foo is a symbol. Also, the "expression separator" should be introduced before it is used in the dynamic array. So perhaps the dynamic array (or all array) examples should be closer to the end. > A method is invoked by sending a message to an object, the message receiver; the message returns an object. A message is an identifier for which objects provide methods of implementation. A method is invoked by sending a message to an object. The object is the /receiver/ of the message. The message returns an object. > Messages syntax mimics natural language Message syntax mimics natural language > Pharo: aColor r: 0.2 g: 0.3 b: 0 This is not very natural language. We only need one Java/Pharo example. Delete this one. > Array new You would never(?) really use that line. So lets not mislead a newcomer who might try it and get frustrated why they can't add items to it. OrderedCollection new is described later, so here perhaps instead use... 2 squared The receiver of the squared message is the object 2, with the object 4 returned. > A keyword message can take one or more arguments that are inserted in the message name. A keyword message can take one or more arguments that are interspersed through the message name. (Put the example of this first, i.e. #to:by: before #allButFirst: > Precedence Message Precedence > Parentheses > unary > binary > keyword, Is too concise. I know the answer but I still feel awkward decoding that line. Better... Message sending order of precedence is: parentheses, unary, binary, keyword, left to right. > (10 between: 1 and: 2 + 4 * 3) not Might be better to one more unary message... (10 between: 1 and: 2 + 4 * 3 negated) not The unary #negated message inside the parentheses is sent first, then #+ as the left most binary message, followed by #*. Then keyword message #between:and: is sent, and finally #not. > The rule suffers no exception: operators The rule suffers no exception. Operators > so 2 + 4 * 3 reads left-to-right and gives 18, not 14! so 2 + 4 * 3 reads left-to-right and gives 18, not 14! Note, comparison operators like equals = is just binary messages, so... 1 * 3 = 3 produces boolean object true but 3 = 3 * 1 produces an error, since a boolean object does not understand multiplication. Hint, while beginning with Pharo, make liberal us of parentheses in calculations to make precedence explicit and thus easy to observe. > OrderedCollection new > add: #abc; > add: #def; > add: #ghi. Rather than just mentioning needing to send #yourself in the text, show the pattern more explicitly by putting it in the example... OrderedCollection new add: #abc; add: #def; add: #ghi; yourself. The message new is sent to OrderedCollection which results in a new collection to which three add: messages are sent. The value of the whole message cascade is the value of the last message sent, so without #yourself this would be the symbol #ghi. With #yourself, the return value is {#abc. #def. #ghi} > Blocks are objects containing code that is executed on demand, > (anonymous functions). They are the basis for control structures > like conditionals and loops. Blocks are objects, that contain code to be executed on demand (anonymous functions). They defined by square brackets and are the basis for control structures like conditionals and loops. > 2 = 2 > ifTrue: [Error signal: âHelpâ]. Lets not mix in additional concepts. How about... 2 = 2 ifTrue: [self inform: 'Equal'] > The first example sends the message ifTrue: to the boolean > true (computed from 2 = 2 ) with a block as argument. >From 2 = 2 comes the boolean object true, to which the #ifTrue: message is sent with the block as argument. The object true always evaluates #ifTrue: arguments, thus the text "Equal' displays on the screen. > As a result, Hello World! is printed. As a result, Hello World! is printed. in the Transcript window (which you from the World > Tools menu) > Pharo is a live programming environment: you can modify your > objects and your code while your program is executing. > â¢ and much, much more! There doesn't seem much use in that line hanging on its lonesome at the top of a column > When a protocol name starts with a *, methods of this protocol belong to a different package A protocol name starting with a * indicates methods belonging to a different package. > To add a package: first column + menu add package To add a package, right-click lower down in the Packages pane. (If they right-click near the top they wont get that option - something I find annoying) > To add a class, edit the proposed template! To add a class, select a package and edit the proposed template. (its not that exciting to need an exclamation mark :) > Counter new . > initialize > super initialize > count := 0 It looks like the first line is part of the rest of the code sample. Also this should be moved beneath the Methods subheading. > Methods are public and virtual. There are always looked up in Methods are public and virtual. They are always looked up in > Class methods follow the same dynamic lookup than instance Class methods follow the same dynamic lookup as instance cheers -ben

April 9, 2016

Re: [Pharo-dev] new pharo cheatsheet

by serge.stinckwich＠gmail.com

Yes you are right. We have 2 students (3rd Year at University) here that have been exposed only to C or Java and they are totally index-intoxicated ... They can't reason on collections. Difficult for them to change their habits. Sent from my iPhone > On 9 avr. 2016, at 11:51, Stephan Eggermont <stephan(a)stack.nl> wrote: > >> On 09-04-16 10:55, Cyril Ferlicot D. wrote: >> I use Pharo since 1 year now and I had to use indexes only 3-4 times. > > Probably on day 1 and 2 :) > The problem is that people new to Smalltalk have a background. > If they have programming experience, it is likely with a language where > indexes are important. Finding out how and when to avoid using them > takes time to learn. And that is exactly when they need the cheatsheet > most. > > Stephan > >

April 9, 2016

Re: [Pharo-dev] new pharo cheatsheet

by Stephan Eggermont

On 09-04-16 10:55, Cyril Ferlicot D. wrote: > I use Pharo since 1 year now and I had to use indexes only 3-4 times. Probably on day 1 and 2 :) The problem is that people new to Smalltalk have a background. If they have programming experience, it is likely with a language where indexes are important. Finding out how and when to avoid using them takes time to learn. And that is exactly when they need the cheatsheet most. Stephan

April 9, 2016

Re: [Pharo-dev] new pharo cheatsheet

by olivier auverlot

@cyril +1 Le 9 avr. 2016 10:56 AM, "Cyril Ferlicot D." <cyril.ferlicot(a)gmail.com> a Ã©crit : > Le 08/04/2016 22:08, J.F. Rick a Ã©crit : > > It looks good. I might mention that most data structures are 1 indexed > > as most other languages tend to be 0 indexed and that throws people new > > to the language. > > > > I use Pharo since 1 year now and I had to use indexes only 3-4 times. I > think it is more important to say that Pharo have Collections with an > awesome API. > > -- > Cyril Ferlicot > > http://www.synectique.eu > > 165 Avenue Bretagne > Lille 59000 France > >

April 9, 2016

Re: [Pharo-dev] new pharo cheatsheet

by Cyril Ferlicot D.

Le 08/04/2016 22:08, J.F. Rick a Ã©crit : > It looks good. I might mention that most data structures are 1 indexed > as most other languages tend to be 0 indexed and that throws people new > to the language. > I use Pharo since 1 year now and I had to use indexes only 3-4 times. I think it is more important to say that Pharo have Collections with an awesome API. -- Cyril Ferlicot http://www.synectique.eu 165 Avenue Bretagne Lille 59000 France

April 9, 2016

Re: [Pharo-dev] new pharo cheatsheet

by philippe.back＠highoctane.be

On Apr 9, 2016 9:54 AM, "olivier auverlot" <olivier.auverlot(a)gmail.com> wrote: > > I think that it could be interesting to use it also on a simple HTML page for the Pharo web site. This document can be put in the main menu ("Beginners" ?) just before "Documentation". > > It's really cool to have a synthesis document for the newcomers. I still have a little Squeak booklet that we could redo for Pharo. It was very useful when I was learning. Phil > > 2016-04-09 8:09 GMT+02:00 Ben Coman <btc(a)openinworld.com>: >> >> On Sat, Apr 9, 2016 at 6:16 AM, Damien Pollet <damien.pollet(a)gmail.com> wrote: >> > On 8 April 2016 at 22:57, Sven Van Caekenberghe <sven(a)stfx.eu> wrote: >> >> >> >> Since we are simpler and more logical, a cheat sheet should not confuse >> >> people by describing what we are not. >> > >> > >> > I beg to disagree. "Simpler and more logical" is just your biased point of >> > view; fact is, zero-based indexing is just more widespread in programming >> > languages. >> > >> > I would be happy to be proven wrong about that, but I seriously doubt most >> > people that come to Smalltalk have never been exposed to programming before. >> > It's not unreasonable to assume that they've started programming in any one >> > of the most popular languages these days, and that that language is >> > zero-indexed. So mentioning that in Smalltalk the first element is indeed at >> > index 1 is pretty essential, if just to lift the ambiguity. >> >> +1. But to follow Sven's point exactly. We don't need to say we are >> "not 0 based", just that we are "1 based". >> >> cheers -ben >> >

April 9, 2016

Re: [Pharo-dev] new pharo cheatsheet

by olivier auverlot

I think that it could be interesting to use it also on a simple HTML page for the Pharo web site. This document can be put in the main menu ("Beginners" ?) just before "Documentation". It's really cool to have a synthesis document for the newcomers. 2016-04-09 8:09 GMT+02:00 Ben Coman <btc(a)openinworld.com>: > On Sat, Apr 9, 2016 at 6:16 AM, Damien Pollet <damien.pollet(a)gmail.com> > wrote: > > On 8 April 2016 at 22:57, Sven Van Caekenberghe <sven(a)stfx.eu> wrote: > >> > >> Since we are simpler and more logical, a cheat sheet should not confuse > >> people by describing what we are not. > > > > > > I beg to disagree. "Simpler and more logical" is just your biased point > of > > view; fact is, zero-based indexing is just more widespread in programming > > languages. > > > > I would be happy to be proven wrong about that, but I seriously doubt > most > > people that come to Smalltalk have never been exposed to programming > before. > > It's not unreasonable to assume that they've started programming in any > one > > of the most popular languages these days, and that that language is > > zero-indexed. So mentioning that in Smalltalk the first element is > indeed at > > index 1 is pretty essential, if just to lift the ambiguity. > > +1. But to follow Sven's point exactly. We don't need to say we are > "not 0 based", just that we are "1 based". > > cheers -ben > >

April 9, 2016