Re: Type hints - am I doing it right?

2023-12-13 Thread Thomas Passin via Python-list

On 12/13/2023 11:17 AM, Mats Wichmann via Python-list wrote:

On 12/13/23 00:19, Frank Millman via Python-list wrote:

I have to add 'import configparser' at the top of each of these 
modules in order to type hint the method.


This seems verbose. If it is the correct way of doing it I can live 
with it, but I wondered if there was an easier way.


Think of import as meaning "make this available in my current (module) 
namespace".


The actual import machinery only runs the first time, that is, if it's 
not already present in the sys.modules dict.


There's also the approach of importing the typing objects conditionally, 
as in this snippet from the Leo Editor 
(https://github.com/leo-editor/leo-editor)


if TYPE_CHECKING:  # pragma: no cover
from leo.core.leoCommands import Commands as Cmdr
from leo.core.leoGui import LeoKeyEvent as Event

Yes, it's more verbose but it makes clear what the intent is.
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Re: Type hints - am I doing it right?

2023-12-13 Thread Mats Wichmann via Python-list

On 12/13/23 00:19, Frank Millman via Python-list wrote:

I have to add 'import configparser' at the top of each of these modules 
in order to type hint the method.


This seems verbose. If it is the correct way of doing it I can live with 
it, but I wondered if there was an easier way.


Think of import as meaning "make this available in my current (module) 
namespace".


The actual import machinery only runs the first time, that is, if it's 
not already present in the sys.modules dict.

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Re: Type hints - am I doing it right?

2023-12-13 Thread Cameron Simpson via Python-list

On 13Dec2023 09:19, Frank Millman  wrote:

I am adding type hints to my code base.

[...]

In the other module I have this -

 def config_database(db_params):

To add a type hint, I now have this -

 def config_database(db_params: configparser.SectionProxy):

To get this to work, I have to add 'import configparser' at the top of 
the module.


I have three separate modules, one for each database, with a subclass 
containing the methods and attributes specific to that database. Each 
one has a connect() method which receives db_params as a parameter. 
Now I have to add 'import configparser' at the top of each of these 
modules in order to type hint the method.


This seems verbose. If it is the correct way of doing it I can live 
with it, but I wondered if there was an easier way.


Not really. It's like any other name - it needs importing if you're 
going to use it.


You can make the hint itself more compact:

from configparser import SectionProxy
...
def config_database(db_params: SectionProxy):

Or you could be a bit more agnostic:

from typing import Mapping
...
def config_database(db_params: Mapping):

since I imagine config_database() would accept any kind of mapping 
(dicts, etc etc).


Cheers,
Cameron Simpson 
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Type hints - am I doing it right?

2023-12-12 Thread Frank Millman via Python-list

Hi all

I am adding type hints to my code base.

I support three databases - sqlite3, Sql Server, PostgreSQL. The db 
parameters are kept in an ini file, under the section name 'DbParams'. 
This is read on program start, using configparser, and passed to a 
function config_database() in another module with the argument 
cfg['DbParams'].


In the other module I have this -

 def config_database(db_params):

To add a type hint, I now have this -

 def config_database(db_params: configparser.SectionProxy):

To get this to work, I have to add 'import configparser' at the top of 
the module.


I have three separate modules, one for each database, with a subclass 
containing the methods and attributes specific to that database. Each 
one has a connect() method which receives db_params as a parameter. Now 
I have to add 'import configparser' at the top of each of these modules 
in order to type hint the method.


This seems verbose. If it is the correct way of doing it I can live with 
it, but I wondered if there was an easier way.


BTW I have realised that I can bypass the problem by converting 
db_params to a dict, using dict(cfg['DbParams']). But I would still like 
an answer to the original question, as I am sure similar situations will 
occur without such a simple solution.


Thanks

Frank Millman

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