how to convert this with a stream

"I have a SortedCollection of Teams.  Now I need to convert *it*

 to a line like ...".

Well, no.  You need to convert *each team* separately to such a

line.  So something like

  aStream nextPutAll: '...header line...'; cr.

  mySortedTeams do: [:eachTeam |

     -write a formatted line describing eachTeam to aStream].

Now it gets interesting.  Whose responsibility is it to write

a representation of a Team instance to a stream?  Should it be

done by the Team instance, or should it be done outside?

Question 1: is there obviously one and only one format, or do

you think that in a more realistic example there might be more

than one way to print a Team object?  I concluded that there

might be many different ways to do it.  (I personally dislike

putting variable length fields on the left.)

Question 2: *Can* it be done from the outside or *must* it be

done inside?  Is there any information in the printed representation

that the caller cannot ask the team object for?  In this case, all

of the information is available through Team's public interface.

Question 3: Should Teams and printing be *coupled*?  Should a Team

know about details like the dividing line between columns?  In this

case, I decided that putting the formatting code inside the Team

object was highly undesirable coupling.

Question 4: Is it *possible* for a Team object to do the formatting

without knowing about all the other Teams in the collection?  In this

case, the specification is rather vague.  It seemed to me that all

the numeric columns should be the same width and should be wide enough

to hold the largest number with a space on each side.

In answer to question 4, my Tournament code contains

   w := mySortedTeams inject: 1 into: [:acc :team |

    (team matchCount max: team points) printString size max: acc].

and this clearly requires knowledge of all the teams, so it makes no

sense to put it in Team. (Of course, if the column widths are fixed,

this argument fails, but such a choice makes no sense for large problems.)

So now you need something like

   aStream nextPutAll: team name; space: 30 - team name size.

and then a numeric value might be written as

   aStream nextPutAll: ' | '; space: w - team points printString size;

     print: team points.

Please do not use << . Historically, << had no meaning in Smalltalk.

In some Smalltalks it means leftwards bit shift.  It is just too

confusing.  (In a shell, you would use > for output, not <<, which

is used for a kind of input.)  It is really weird to use s << String cr

instead of s cr.  So idomatic Smalltalk would be

  s nextPutAll: t name; cr.

Why are you writing to (an output stream over) an Array?
Surely you want a String?

But in any case, I would split this into two methods:

  printTeams: teams on: aStream

    -- print heading --

    -- print each team --

  printTeamsAsString: teams

    ^String streamContents: [:s | self printTeams: teams on:s]

On Wed, 27 Mar 2019 at 07:12, Roelof Wobben <[hidden email]> wrote:

Hello,

I have a SortedCollection of teams.

Now I need to convert this to a line like this :

'Allegoric Alaskans             |  1 |  1 |  0 |  0 |  3'

I tried it with this :

outcome := Array
         streamContents: [ :s |
             TeamStatusSorted
                 do: [ :each |
                     s << each name.
                     s << String cr ] ].
     ^ outcome


or String streamContents but it will not give me the right answer,
So please some hints how I can make this work.

Roelof