Can you do true lazy imports on typer?

[foxtbirdy]

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Example Code

import typer

from test import merge
from test import compress
from test import check

app = typer.Typer()

app.command(help="....")(merge.merge)
app.command(help="....")(compress.compress)
app.command(help="....")(checkhealth.checkhealth)

Description

I have wrote a program called pdfsimuti that combines the feature of several PDF utility tools into a single CLI application. This includes watermarking, merging, compressing, splitting etc. All these modules import some heavy packages which reduces responds time on my machine. I wanted to make my program fast by importing only the modules that is called.

If I wanted to use a module like merge, I would go something like python main.py merge --help. But I ran into a problem with the other imports.

To add the module on typer, I have to do something like this,

from pdfsimuti import merge
from pdfsimuti import compress
from pdfsimuti import checkhealth

app = typer.Typer()

app.command(help="....")(merge.merge)
app.command(help="....")(compress.compress)
app.command(help="....")(checkhealth.checkhealth)

so that it shows the module's short help when python main.py --help is called.

this is where the issue starts. Each of this modules has a lot of global variables tied to imports. Despite doing encapsulations, it still isn't enough. If I do something like python main.py merge file.pdf then it also calls compress and watermark as well.

When they are called, their entire global variables are triggered. I do not need them to be called unless they are needed.

To use lazy imports on them, I have tried this~

@app.command(help="....")
def merge(params1, params2):
    from pdfsimuti import merge
    merge(params1, params2)

but I have ran into another issue. The modules uses enum choices which is present only on the modules file itself. Not only that, the merge parameters also have their own typer properties as well which isn't shown when python main.py merge--help gets called.

Before,

> pdfsimuti checkhealth --help

                                                                                                                                                                                                                                     
 Usage: pdfsimuti checkhealth [OPTIONS]                                                                                                                                                                                              

 Shows you the status of the packages required for the program.

╭─ Options ─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╮
│ --verbose  -v,-V      INTEGER RANGE [x<=3]  Verbose level [default: 1]                                                                                                                                                            │
│ --help     -h                               Show this message and exit.                                                                                                                                                           │
╰───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╯

(

After my attempt on lazy imports,

> pdfsimuti checkhealth --help
                                                                                                                                                                                                                       
 Usage: pdfsimuti checkhealth [OPTIONS] VERBOSE                                                                                                                                                                                      

 Shows you the status of the packages required for the program.

╭─ Arguments ───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╮
│ *    verbose      TEXT  [default: None] [required]                                                                                                                                                                                │
╰───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╯
╭─ Options ─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╮
│ --help  -h        Show this message and exit.                                                                                                                                                                                     │
╰───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╯

Even if I attempt something like

def checkhealth(verbose: Annotated[int, typer.Option("--verbose", "-v", "-V", count=True, max=3, help="Verbose level")] = 1):
    from pdfsimuti import checkhealth
    checkhealth(verbose)

on the main.py, it won't solve the case if enum choices are used as they are not available on main.py

Conclusion

I want to have my modules imported in such way that~

1. they are imported only when they are called.
2. their --help properties are displayed.
3. their parameter's --help properties are displayed in such way even if they have enum choices, they will be displayed

Operating System

Windows

Operating System Details

Windows 11 Version 24H2

Typer Version

0.12.5

Python Version

python 3.13.2

Additional Context

[YuriiMotov]

but I have ran into another issue. The modules uses enum choices which is present only on the modules file itself. Not only that, the merge parameters also have their own typer properties as well which isn't shown when python main.py merge--help gets called.

To overcome this you can move the definitions of types to a separate module and import it unconditionally.

pdfsimuti/types.py

class MyEnum(Enum):
    ...

class OtherType():
    ...

pdfsimuti/merge.py

from pdfsimuti.types import MyEnum, OtherType

...

main.py

from pdfsimuti.types import MyEnum, OtherType
...

@app.command(help="....")
def merge(params1: MyEnum, params2: OtherType):
    from pdfsimuti import merge
    merge(params1, params2)