Would this work for you?
import struct
floatval = 0.6441726684570312
s = struct.pack("d", floatval) # converts floatval into a string (Python
2) or bytes (Python 3), of 8 raw bytes
# then serialise s
To be portable between different platforms, you would also need to store
whether the format
is little-endian or big-endian (sys.byteorder is 'big' or 'little'; I
don't know what it does on bi-endian machines).
Rob Cliffe
On 08/08/2019 20:05:50, Richard Musil wrote:
I am not sure `(str(o),)` is what I want. For a comparison here are three
examples:
```
json:orig = {"val": 0.6441726684570313}
json:pyth = {'val': 0.6441726684570312}
json:seri = {"val": 0.6441726684570312}
dson:orig = {"val": 0.6441726684570313}
dson:pyth = {'val': Decimal('0.6441726684570313')}
dson:seri = {"val": ["0.6441726684570313"]}
sjson:orig = {"val": 0.6441726684570313}
sjson:pyth = {'val': Decimal('0.6441726684570313')}
sjson:seri = {"val": 0.6441726684570313}
```
Each one has three outputs, `orig` is the input text, `pyth` is its python
representation in a `dict`, `seri` is the serialized text output of `pyth`.
Now, the prefixes are `json` for standard Python module (which gets the last
digit different from the output). `dson` is standard Python module using
`parse_float=decimal.Decimal` on `json.loads` and custom serializer with
proposed `return (str(o),)`. Finally `sjson` is `simplejson` using
`use_decimal=True` on `json.loads` and the same (which is default) on its
`json.dumps`.
When I had `return str(o)` in the custom impl. I ended up with the string in
the output:
```
dson:orig = {"val": 0.6441726684570313}
dson:pyth = {'val': Decimal('0.6441726684570313')}
dson:seri = {"val": "0.6441726684570313"}
```
and finally, with `return float(o)` I am basically back at the square one:
```
dson:orig = {"val": 0.6441726684570313}
dson:pyth = {'val': Decimal('0.6441726684570313')}
dson:seri = {"val": 0.6441726684570312}
```
The possibility to specify the "raw" textual output, which does not get mangled
by the JSONEncoder when custom encoder is used seems to be missing.
˙``
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