new pharo cheatsheet

Hi Sven,

On Mar 8, 2018, at 9:55 AM, Sven Van Caekenberghe <[hidden email]> wrote:

On 8 Mar 2018, at 17:58, Eliot Miranda <[hidden email]> wrote:

Hi Stef,

following on from Sean, (+1000 for using ordinary quotes)

’string’ collection of characters => ’string’ sequence of characters

$a, Character space Two ways to create characters => $a, Character space two ways to denote characters (or two ways to write characters; all other explanations in this list are not capitalized; this shouldn't be either)

exp1. exp2 expression separator => expr1. expr2 statement separator

; message cascade => expr doThis ; doThat   semicolon - message cascade (c.f. exp1. exp2 expression separator)

^ expr caret - returns a result from a method => ^ expr caret - return a result from a method (or, ParcPlace preference, answer a result from a method, since we're sending messages here)

...

A unary message is one with no arguments. => A unary message has no arguments. (c.f. A binary message takes only one argument ...)

...

Set new add: 4; add: 4 ; yourself ~> aSet => Set new add: 4; add: 4 ; yourself ~> aSet(4)

Dictionary new at: #a put: 'Alpha' ; yourself a Dictionary => Dictionary new at: #a put: 'Alpha' ; yourself a Dictionary(#a->'Alpha' )

and then in the Files and Stream section I would give two more examples of exactly the same sequence that use the convenience APIs.  This is the existing text:

   work := FileSystem disk workingDirectory.

   stream := (work / ’foo.txt’) writeStream.

   stream nextPutAll: ’Hello World’.

   stream close.

   stream := (work / ’foo.txt’) readStream.

   stream contents.                                     ~> 'Hello World'

   stream close.

I would make it read

   work := FileSystem disk workingDirectory.

   stream := (work / ’foo.txt’) writeStream.

   stream nextPutAll: ’Hello World’.

   stream close.

   stream := (work / ’foo.txt’) readStream.

   stream contents.                                     ~> 'Hello World'

   stream close.

   or, more simply

   work := FileSystem disk workingDirectory.

   (work / ’foo.txt’) writeStreamDo: [ :fileStream | fileStream nextPutAll: ’Hello World’ ].

   (work / ’foo.txt’) readStreamDo: [ :fileStream | fileStream contents]                            ~> 'Hello World'

   or, more simply still

   work := FileSystem disk workingDirectory.

   (work / ’foo.txt’) writeStreamDo: [ :fileStream | fileStream nextPutAll: ’Hello World’ ].

   (work / ’foo.txt’) contents                                                                                             ~> 'Hello World'

file := FileSystem disk workingDirectory / 'foo' , 'txt'.
file ensureDelete.
file writeStreamDo: [ :fileStream | fileStream nextPutAll: 'Hello World' ].
file contents.
file delete.

(to make it re-entrant and a bit more concise)

that suggests 

file := FileSystem disk workingDirectory / 'foo' , 'txt'.
file newWriteStreamDo: [ :fileStream | fileStream nextPutAll: 'Hello World' ].
file contents.
file delete.

where newWriteStreamDo: includes the file ensureDelete, or better still a truncation, which saves the effort of deletion but (I *think*) has the same effect.

+1e10 for plain single quotes, VERY important.

or if you can't make it fit, just give the last version

Finally, this seems to have fallen off the end:

A simple, uniform and powerful model

Pharo has a simple dynamically-typed object model:

Perhaps shrink the picture of the browser.  You can save three lines by writing

   OrderedCollection new

       add: 1;

       add: 2;

       add: 3.

as OrderedCollection new add: 1; add: 2; add: 3.

And another by writing 2=2 ifTrue: [ Error signal: ’Help’ ]. on one line.

HTH

On Fri, Apr 8, 2016 at 12:56 PM, stepharo <[hidden email]> wrote:

new cheatsheet for Pharo syntax.

Any feedback is welcome

Stef

--

_,,,^..^,,,_

best, Eliot