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Class: PrintConverter


Inheritance:

   Object
   |
   +--PrintConverter

Package:
stx:libview2
Category:
Interface-Support
Version:
rev: 1.23 date: 2018/05/06 11:12:45
user: cg
file: PrintConverter.st directory: libview2
module: stx stc-classLibrary: libview2
Author:
Claus Gittinger

Description:


printConverters can be used with labels and editFields to convert 
an object to/from some printed representation.

Conversion is done via two blocks, which can be set at instance
creation time - either as custom blocks or as one of the
standard conversions. 

There are a number of standard setups for common conversions; 
if none of them fits your needs, 
create a custom converter by defining its two conversion blocks.

Notice: this class was implemented using protocol information
from alpha testers - it may not be complete or compatible to
the corresponding ST-80 class. If you encounter any incompatibilities,
please forward a note to the ST/X team.


Class protocol:

instance creation
o  new

utilities
o  print: aNumber formattedBy: formatString
take the digits of aNumbers printString, and squash them
into formatString, where #-characters are replaced by
successive characters from the printString.
Warning: use with care - it does not check for decimal points etc.
the printString of aNumber must have enough digits for all
#-characters to be replaced.
Therefore, precheck the numbers value and use appropriate format
strings then.
For number formatting, see also: printfPrintString: implementations.
usage example(s):
     PrintConverter print:'123456789' formattedBy:'US$ ###,###.##' 

    fails for:
     PrintConverter print:'1234' formattedBy:'US$ ###,###.##' 

    invalid string for:
     PrintConverter print:'123456789' formattedBy:'US$ ###' 


Instance protocol:

accessing
o  type
return the type if it's one of the standard converters,
#number, #string etc. nil otherwise

converting
o  printStringFor: aValue
sent when an inputField wants a models value to be converted to a string
for display

o  readValueFrom: aString
sent when an inputField wants a string to be converted to a value
to be returned as its contents value

initialization
o  initFor: aTypeSymbol
initialize to convert to/from objects as specified by aTypeSymbol,
which may be one of #number, #string, #symbol, #date or #password ...

o  initForDate
initialize to convert to/from a date
- if the string is empty or invalid, convert to the current date

o  initForDateOrNil
initialize to convert to/from a date
- if the string is empty or invalid, convert to nil

o  initForFloat
initialize to convert to/from an float
- if the string is empty or invalid, convert to 0

o  initForFloatWithPrecision: nDigits
initialize to convert to/from an float with nDigits after the decimal point
(truncating remaining digits).
- if the string is empty or invalid, convert to 0

o  initForInteger
initialize to convert to/from an integer
- if the string is empty or invalid, convert to 0

o  initForIntegerOrNil
initialize to convert to/from an integer
- if the string is empty or invalid, convert to nil

o  initForNumber
initialize to convert to/from a number
- if the string is empty or invalid, convert to 0

o  initForNumberOrNil
initialize to convert to/from a number
- if the string is empty or invalid, convert to nil

o  initForString
initialize for a string - this is trivial

o  initForTime
initialize to convert to/from a time
- if the string is empty or invalid, convert to the current time

o  initForTimeOrNil
initialize to convert to/from a time
- if the string is empty or invalid, convert to nil

o  initForYesNo
initialize to convert a 'yes'/'no' string to/from a boolean
The string is supposed to be in the current Language
(i.e. if german, ja/nein has to be entered.
Invalid entries are converted to false.

o  toPrint: printBlock toRead: readBlock
initialize to convert using two custom blocks.
printBlock is supposed to get the objects value as argument,
and to return a string.
readBlock is supposed to get a string as argument, and return
the corresponding object.


Examples:


stupid examples: convert date <-> string:
    |conv|

    conv := (PrintConverter new)
                toPrint:[:date | date printString]
                toRead:[:string | Date readFromString:string].
    (conv printStringFor:(Date today)) inspect.
    (conv readValueFrom:(Date today printString)) inspect
convert number <-> string:
    |conv|

    conv := (PrintConverter new) initForNumber.
    (conv printStringFor:12345) inspect.
    (conv readValueFrom:'12345') inspect
convert boolean <-> string:
    |conv|

    conv := (PrintConverter new) initForYesNo.
    (conv printStringFor:true).  
    (conv printStringFor:false).    
    (conv readValueFrom:'yes').  
    (conv readValueFrom:'no').  
    'if language is #de:'.
    (conv readValueFrom:'ja').    
    (conv readValueFrom:'nein')  
concrete examples: convert in an inputField:
    |dialog field|

    dialog := Dialog new.
    dialog addTextLabel:'a number (and only numbers):'.
    dialog addVerticalSpace.
    field := dialog addInputFieldOn:(0 asValue).
    field converter:(PrintConverter new initForNumber).
    field immediateAccept:true.
    dialog addOkButton.
    dialog open.
    dialog accepted ifTrue:[
        Transcript showCR:field editValue
    ]
convert a models value for a label:
    |top v1 v2 l1 l2|

    v1 := 0 asValue.
    v2 := Date today asValue.

    top := StandardSystemView new.
    top extent:200@200.

    l1 := Label origin:0.0@0.0 corner:1.0@0.5 in:top.
    l1 converter:(PrintConverter new initForInteger).
    l1 model:v1; labelMessage:#value; aspect:#value.
    l1 level:-1; inset:10.

    l2 := Label origin:0.0@0.5 corner:1.0@1.0 in:top.
    l2 converter:(PrintConverter new initForDate).
    l2 model:v2; labelMessage:#value; aspect:#value.
    l2 level:-1; inset:10.

    top open.

    'now, change the values ...'.
    [
      1 to:50 do:[:i|
          v1 value:(v1 value + 1).
          v2 value:(v2 value addDays:1).
          (Delay forSeconds:0.5) wait
      ]
    ] fork
convert a models value for a label with limited precision float conversion:
    |top v l1 l2|

    v := 0.0 asValue.

    top := StandardSystemView new.
    top extent:200@200.

    l1 := Label origin:0.0@0.0 corner:1.0@0.5 in:top.
    l1 converter:(PrintConverter new initForFloat).
    l1 model:v; labelMessage:#value; aspect:#value.
    l1 level:-1; inset:10.

    l2 := Label origin:0.0@0.5 corner:1.0@1.0 in:top.
    l2 converter:(PrintConverter new initForFloatWithPrecision:2).
    l2 model:v; labelMessage:#value; aspect:#value.
    l2 level:-1; inset:10.

    top open.

    'now, change the values ...'.
    [
      1 to:100 do:[:i|
          v value:(v value + 0.005).
          (Delay forSeconds:0.5) wait
      ]
    ] fork
a custom converter, converting a number to either 'odd' or 'even' strings (we only need a one-way converter for labels):
    |top v l1 l2|

    v := 0 asValue.

    top := StandardSystemView new.
    top extent:200@200.

    l1 := Label origin:0.0@0.0 corner:1.0@0.5 in:top.
    l1 converter:(PrintConverter new initForInteger).
    l1 model:v; labelMessage:#value; aspect:#value.
    l1 level:-1; inset:10.

    l2 := Label origin:0.0@0.5 corner:1.0@1.0 in:top.
    l2 converter:(PrintConverter 
                    new 
                        toPrint:[:num | num even ifTrue:['even'] 
                                                 ifFalse:['odd']]
                        toRead:[:string | ]).
    l2 model:v; labelMessage:#value; aspect:#value.
    l2 level:-1; inset:10.

    top open.

    'now, change the values ...'.
    [
      1 to:100 do:[:i|
          v value:(v value + 1).
          (Delay forSeconds:0.5) wait
      ]
    ] fork
see more examples in the EditField examples.

ST/X 7.1.0.0; WebServer 1.663 at exept.de:8081; Sun, 22 Jul 2018 16:44:54 GMT