Class: PrintConverter

• Inheritance
• Description
• Class protocol
  • instance creation
  • utilities
• Instance protocol
  • accessing
  • converting
  • initialization
• Examples

Inheritance:

   Object
   |
   +--PrintConverter

Package:

stx:libview2

Category:

Interface-Support

Version:

rev: 1.25 date: 2023/06/15 18:39:10

user: cg

file: PrintConverter.st directory: libview2

module: stx stc-classLibrary: libview2

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.

copyright
COPYRIGHT (c) 1995 by Claus Gittinger
             All Rights Reserved

This software is furnished under a license and may be used
only in accordance with the terms of that license and with the
inclusion of the above copyright notice.   This software may not
be provided or otherwise made available to, or used by, any
other person.  No title to or ownership of the software is
hereby transferred.

Class protocol:

 new

(comment from inherited method)
return an instance of myself without indexed variables

 print: aNumber formattedBy: formatString

take the digits of aNumber's 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 number's 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:

 type

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

 printStringFor: aValue

sent when an inputField wants a models value to be converted to a string
for display

 readValueFrom: aString

sent when an inputField wants a string to be converted to a value
to be returned as its contents value

 initFor: aTypeSymbol

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

 initForDate

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

 initForDateOrNil

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

 initForFloat

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

 initForFloatRoundedToPrecision: nDigits

initialize to convert to/from an float with nDigits after the decimal point
(rounding the last digit).
- if the string is empty or invalid, convert to 0

 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

 initForInteger

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

 initForIntegerOrNil

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

 initForNumber

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

 initForNumberOrNil

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

 initForString

initialize for a string - this is trivial

 initForTime

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

 initForTimeOrNil

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

 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.

 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:

    |conv|

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

    |conv|

    conv := (PrintConverter new) initForNumber.
    (conv printStringFor:12345) inspect.
    (conv readValueFrom:'12345') inspect

    |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')  

    |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
    ]

    |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

    |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

    |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