Re: [Pharo-dev] FileSystem tweaks (was Re: new pharo cheatsheet)

2018-03-08 19:44 GMT+01:00 Eliot Miranda <eliot.miranda@gmail.com>:

Hi Sven,

On Mar 8, 2018, at 9:55 AM, Sven Van Caekenberghe <sven@stfx.eu> wrote:

On 8 Mar 2018, at 17:58, Eliot Miranda <eliot.miranda@gmail.com> 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.

Hi Eliot, not exactly the same effect wrt file access rights.

+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 <stepharo@free.fr> wrote:

new cheatsheet for Pharo syntax.

Any feedback is welcome

Stef

--

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

best, Eliot