How to create class attribute that is an alteration of the same class attribute
I have the following class:
@dataclass
class thing:
DATE: datetime.datetime
BEG_DATE: datetime.datetime = self.DATE.replace(day=1))
But I get this error:
NameError("name 'DATE' is not defined")
Visual Studio points to line 4 where I'm trying to define BEG_DATE.
1) Why?
2) How can I create the attribute BEG_DATE that takes the DATE attribute and just changes the day to 1?
I've tried field(default_factory=self.DATE.replace(day=1)), but I got the same error.
python python-3.7
edited Nov 12 '18 at 15:22
Joel
1,5726719
asked Nov 12 '18 at 7:00
JarrodJarrod
1021110
add a comment |
I have the following class:
@dataclass
class thing:
DATE: datetime.datetime
BEG_DATE: datetime.datetime = self.DATE.replace(day=1))
But I get this error:
NameError("name 'DATE' is not defined")
Visual Studio points to line 4 where I'm trying to define BEG_DATE.
1) Why?
2) How can I create the attribute BEG_DATE that takes the DATE attribute and just changes the day to 1?
I've tried field(default_factory=self.DATE.replace(day=1)), but I got the same error.
python python-3.7
edited Nov 12 '18 at 15:22
Joel
1,5726719
asked Nov 12 '18 at 7:00
JarrodJarrod
1021110
@stovfl it is valid Python. Read up on post-init processing
– Joel
Nov 12 '18 at 15:12
@Joel: Thank you for pointing that out.
– stovfl
Nov 12 '18 at 15:16
add a comment |
I have the following class:
@dataclass
class thing:
DATE: datetime.datetime
BEG_DATE: datetime.datetime = self.DATE.replace(day=1))
But I get this error:
NameError("name 'DATE' is not defined")
Visual Studio points to line 4 where I'm trying to define BEG_DATE.
1) Why?
2) How can I create the attribute BEG_DATE that takes the DATE attribute and just changes the day to 1?
I've tried field(default_factory=self.DATE.replace(day=1)), but I got the same error.
python python-3.7
edited Nov 12 '18 at 15:22
Joel
1,5726719
asked Nov 12 '18 at 7:00
JarrodJarrod
1021110
I have the following class:
@dataclass
class thing:
DATE: datetime.datetime
BEG_DATE: datetime.datetime = self.DATE.replace(day=1))
But I get this error:
NameError("name 'DATE' is not defined")
Visual Studio points to line 4 where I'm trying to define BEG_DATE.
1) Why?
2) How can I create the attribute BEG_DATE that takes the DATE attribute and just changes the day to 1?
I've tried field(default_factory=self.DATE.replace(day=1)), but I got the same error.
python python-3.7
python python-3.7
edited Nov 12 '18 at 15:22
Joel
1,5726719
asked Nov 12 '18 at 7:00
JarrodJarrod
1021110
edited Nov 12 '18 at 15:22
Joel
1,5726719
asked Nov 12 '18 at 7:00
JarrodJarrod
1021110
edited Nov 12 '18 at 15:22
Joel
1,5726719
edited Nov 12 '18 at 15:22
Joel
1,5726719
edited Nov 12 '18 at 15:22
Joel
1,5726719
1,5726719
asked Nov 12 '18 at 7:00
JarrodJarrod
1021110
asked Nov 12 '18 at 7:00
JarrodJarrod
1021110
asked Nov 12 '18 at 7:00
JarrodJarrod
1021110
1021110
@stovfl it is valid Python. Read up on post-init processing
– Joel
Nov 12 '18 at 15:12
@Joel: Thank you for pointing that out.
– stovfl
Nov 12 '18 at 15:16
add a comment |
@stovfl it is valid Python. Read up on post-init processing
– Joel
Nov 12 '18 at 15:12
@Joel: Thank you for pointing that out.
– stovfl
Nov 12 '18 at 15:16
@stovfl it is valid Python. Read up on post-init processing
– Joel
Nov 12 '18 at 15:12
@stovfl it is valid Python. Read up on post-init processing
– Joel
Nov 12 '18 at 15:12
@Joel: Thank you for pointing that out.
– stovfl
Nov 12 '18 at 15:16
@Joel: Thank you for pointing that out.
– stovfl
Nov 12 '18 at 15:16
add a comment |
1 Answer
1
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For fields that depend on the values of other fields, you need to take advantage of Post-init processing. The way you're doing it now, Python is trying to evaluate self.DATE.replace(day=1) when the class is created, rather than when the instance is created.
from dataclasses import dataclass, field
@dataclass
class thing:
DATE: datetime.datetime
BEG_DATE: datetime.datetime = field(init=False)
def __post_init__(self):
self.BEG_DATE = self.DATE.replace(day=1))
answered Nov 12 '18 at 15:01
Patrick HaughPatrick Haugh
27.8k82546
add a comment |
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1 Answer
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1 Answer
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For fields that depend on the values of other fields, you need to take advantage of Post-init processing. The way you're doing it now, Python is trying to evaluate self.DATE.replace(day=1) when the class is created, rather than when the instance is created.
from dataclasses import dataclass, field
@dataclass
class thing:
DATE: datetime.datetime
BEG_DATE: datetime.datetime = field(init=False)
def __post_init__(self):
self.BEG_DATE = self.DATE.replace(day=1))
answered Nov 12 '18 at 15:01
Patrick HaughPatrick Haugh
27.8k82546
add a comment |
For fields that depend on the values of other fields, you need to take advantage of Post-init processing. The way you're doing it now, Python is trying to evaluate self.DATE.replace(day=1) when the class is created, rather than when the instance is created.
from dataclasses import dataclass, field
@dataclass
class thing:
DATE: datetime.datetime
BEG_DATE: datetime.datetime = field(init=False)
def __post_init__(self):
self.BEG_DATE = self.DATE.replace(day=1))
answered Nov 12 '18 at 15:01
Patrick HaughPatrick Haugh
27.8k82546
add a comment |
For fields that depend on the values of other fields, you need to take advantage of Post-init processing. The way you're doing it now, Python is trying to evaluate self.DATE.replace(day=1) when the class is created, rather than when the instance is created.
from dataclasses import dataclass, field
@dataclass
class thing:
DATE: datetime.datetime
BEG_DATE: datetime.datetime = field(init=False)
def __post_init__(self):
self.BEG_DATE = self.DATE.replace(day=1))
answered Nov 12 '18 at 15:01
Patrick HaughPatrick Haugh
27.8k82546
For fields that depend on the values of other fields, you need to take advantage of Post-init processing. The way you're doing it now, Python is trying to evaluate self.DATE.replace(day=1) when the class is created, rather than when the instance is created.
from dataclasses import dataclass, field
@dataclass
class thing:
DATE: datetime.datetime
BEG_DATE: datetime.datetime = field(init=False)
def __post_init__(self):
self.BEG_DATE = self.DATE.replace(day=1))
answered Nov 12 '18 at 15:01
Patrick HaughPatrick Haugh
27.8k82546
answered Nov 12 '18 at 15:01
Patrick HaughPatrick Haugh
27.8k82546
answered Nov 12 '18 at 15:01
Patrick HaughPatrick Haugh
27.8k82546
answered Nov 12 '18 at 15:01
Patrick HaughPatrick Haugh
27.8k82546
27.8k82546
add a comment |
add a comment |
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@stovfl it is valid Python. Read up on post-init processing
– Joel
Nov 12 '18 at 15:12
@Joel: Thank you for pointing that out.
– stovfl
Nov 12 '18 at 15:16