HJ Blog > Code Snippet #307: daysSince

2008-12-05 08:58:09 daysSince

A tiny script I needed a few times to quickly tell me how many days it's been since a given date at the command line. I wrote it in f-script (i.e., this is Mac-specific). I could have compressed the code in the middle, but I wanted to keep it ultra-understandable. (As as side-note, "NSDate date" means today's date.)

Post other versions in other languages if you feel so inclined.

( fscript ) ✂

#!/usr/bin/fscript
(sys args count > 0) ifTrue:[
    
    then := NSDate dateWithNaturalLanguageString:(sys args at:0).
    seconds := NSDate date timeIntervalSinceDate:then.
    secsPerDay := 60 * 60 * 24.
    days := seconds / secsPerDay.
    sys out println:(days stringValue) ++ ' days ago'. 

] ifFalse:[ sys out println:'usage: daysSince (date)' ].

  1  #!/usr/bin/fscript
  2  (sys args count > 0) ifTrue:[
  3      
  4      then := NSDate dateWithNaturalLanguageString:(sys args at:0).
  5      seconds := NSDate date timeIntervalSinceDate:then.
  6      secsPerDay := 60 * 60 * 24.
  7      days := seconds / secsPerDay.
  8      sys out println:(days stringValue) ++ ' days ago'. 
  9  
 10  ] ifFalse:[ sys out println:'usage: daysSince (date)' ].

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Jeff (Mon, December 15th, 2008, 6:04pm UTC)

I'll add a Python version here. I thought Python might have a more elegant way to handle this, and perhaps someone knows how to make this more natural.

( python ) ✂

#!/usr/bin/python
import datetime, sys

if len( sys.argv )!=2:
        print "Usage: daysSince (date)"
else:
        today = datetime.date.today()
        year, month, day = [ int(i) for i in sys.argv[1].split( '-' ) ]
        then = datetime.date( year, month, day )
        print str( (today-then).days ) + " days ago"

  1  #!/usr/bin/python
  2  import datetime, sys
  3  
  4  if len( sys.argv )!=2:
  5          print "Usage: daysSince (date)"
  6  else:
  7          today = datetime.date.today()
  8          year, month, day = [ int(i) for i in sys.argv[1].split( '-' ) ]
  9          then = datetime.date( year, month, day )
 10          print str( (today-then).days ) + " days ago"

Philippe Mougin (Mon, January 12th, 2009, 2:30pm UTC)

Hi Jeff,

I see a couple of potentially interesting simplifications in the F-Script code :

NSDate dateWithNaturalLanguageString:(sys args at:0)

can be repalced by:

(sys args at:0) asDate

-------

NSDate date timeIntervalSinceDate:then

can be replaced by

NSDate date — then

In addition, you don't need to surround "sys args count > 0" and "days stringValue" with parentheses.

Jeff (Mon, January 12th, 2009, 3:09pm UTC)

Thanks for the info, Philippe. I think I'll still keep the parentheses for clarity, but I'm really happy to learn about the NSDate algebra and the asDate method. I also then added a check on the then date, which I should have had in there to begin with.

So here's the updated script here:
( fscript ) ✂

#!/usr/bin/fscript
(sys args count > 0) ifTrue:[
    
    then := (sys args at:0) asDate.
    (then==nil) ifFalse:[

        seconds := NSDate date — then.
        daysPerSec := 60 * 60 * 24.
        days := seconds / daysPerSec.
        sys out println:(days stringValue) ++ ' days ago'.
    
    ] ifTrue:[ sys out println:'invalid date string' ]

] ifFalse:[ sys out println:'usage: daysSince (date)' ].

  1  #!/usr/bin/fscript
  2  (sys args count > 0) ifTrue:[
  3      
  4      then := (sys args at:0) asDate.
  5      (then==nil) ifFalse:[
  6  
  7          seconds := NSDate date — then.
  8          daysPerSec := 60 * 60 * 24.
  9          days := seconds / daysPerSec.
 10          sys out println:(days stringValue) ++ ' days ago'.
 11      
 12      ] ifTrue:[ sys out println:'invalid date string' ]
 13  
 14  ] ifFalse:[ sys out println:'usage: daysSince (date)' ].