date of 1 year ago

[zuerrong]

Hello,

How does ruby get the date of 1 year ago?
like the result of with shell command:

date -d '1 year ago'

Thanks.

 

[Stu]

nice. never knew you could do that with the shell command date.

Here is a simple metaprogramming example

class Integer

def days
sec = min = 60
day = 24
return( self * ( day * (sec * min)))
end

def years
return( 365.days)
end

def ago
return( Time.now - self)
end

end

 

[zuerrong]

does every year have the exact days of 365? no, IMO.

 

[Stu]

sorry try this one

class Integer

def days
sec =3D min =3D 60
day =3D 24
return( self * ( day * (sec * min)))
end

def years
year =3D 365
return( year * self.days)
end

def ago
return( Time.now - self)
end

end

 

[OZAWA Sakuro]

nice. never knew you could do that with the shell command date.

Remember it is one of GNU date's extension and is not portable.
http://www.opengroup.org/onlinepubs/009695399/utilities/date.html

$ uname -a
Darwin pisces.local 9.8.0 Darwin Kernel Version 9.8.0: Wed Jul 15
16:55:01 PDT 2009; root:xnu-1228.15.4~1/RELEASE_I386 i386 i386 iMac9,1
Darwin

$ /opt/local/bin/gdate -d '1 year ago'
Wed Nov 25 12:35:00 JST 2009

$ /bin/date -d '1 year ago'
usage: date [-jnu] [-d dst] [-r seconds] [-t west] [-v[+|-]val[ymwdHMS]] ...
[-f fmt date | [[[mm]dd]HH]MM[[cc]yy][.ss]] [+format]

 

[Stu]

Remember it is one of GNU date's extension and is not portable.
http://www.opengroup.org/onlinepubs/009695399/utilities/date.html

Thank you for the heads up. I'm on FreeBSD which should be the same
`date` as Darwin. I'm gonna look at my funtoo box later and read the
man page.

does every year have the exact days of 365? no, IMO.

Date has leap years if your looking for that. Time can do epoch,utc etc.

 

[zuerrong]

=C2=A0def years
=C2=A0 =C2=A0year =3D 365

Well, how do you know every year has exactly 365 days?
I don't think this is a standard method for date calc.

 

[Klaus Stein]

How does ruby get the date of 1 year ago?
like the result of with shell command:

date -d '1 year ago'

Lets use the Date class:

d = Date.today
onyearago = Date.civil(d.year-1, d.month, d.day)

puts onyearago.asctime

Have fun!

Klaus

 

[Stu]

Well, how do you know every year has exactly 365 days?
I don't think this is a standard method for date calc.

I was just trying to get you to closer to the syntax of your gnu date
program. As I mentioned Date has it's own leap year boolean object. Of
course you can always program your own leap year algorithm with a
couple modulo operations. This way year can return the extra day you
get every four years.

Good luck and happy hacking =3D)

 

[rlf]

I was just trying to get you to closer to the syntax of your gnu date
program. As I mentioned Date has it's own leap year boolean object. Of
course you can always program your own leap year algorithm with a
couple modulo operations. This way year can return the extra day you
get every four years.

Good luck and happy hacking =)

Besides overriding the plus and minus operators to deal with days, the
Date class also employs the shift operators to deal with months. So
try:

Date.today << 12

It deals with the leap year issue as well.

 

[Reid Thompson]

Hello,

How does ruby get the date of 1 year ago?
like the result of with shell command:

date -d '1 year ago'

Thanks.

google ruby + chronic

sudo gem install chroni