please add get original value funcion

[piyongcai]

in current decimal，IntPart Function to get decimal IntPart value

// IntPart returns the integer component of the decimal.
func (d Decimal) IntPart() int64 {
	scaledD := d.rescale(0)
	return scaledD.value.Int64()
}

BUT, IN SOM TIME, NEED TO GET ORIGINAL VALUE

eg: PROTOBUF , you need define Decimal message, and you need convert between proto.Decimal and decimal.Decimal

so, it's really neet to to get original value function,

To get this purpose, I copied decimal code, and Add Int64Value function

PLEASE ADD

PLEASE ADD

PLEASE ADD

// Int64Value returns the original  value.
func (d Decimal) Int64Value() int64 {
	return d.value.Int64()
}

the follw code is my proto Decimal define：

// Example: 12345.6789 -> { units = 12345, nanos = 678900000 }
message Decimal {

  // Whole units part of the amount
  int64 val = 1;

  // Nano units of the amount (10^-9)
  // Must be same sign as units
  int32 exp = 2;
}

convert between decimal.Decimal and proto.Decimal

1、decimal.Decimal -> proto.Decimal

func FromDecimal(d decimal.Decimal) *proto.Decimal {
	return &Decimal{
		Val: d.Int64Value(),
		Exp: d.Exponent(),
	}
}

2、proto.Decimal -> decimal.Decimal

func (x proto.Decimal) ToDecimal() decimal.Decimal {
	return decimal.New(x.Val, x.Exp)
}

[mwoss]

Hi @piyongcai! That sounds like a good idea, I will add your request to my backlog.
In the meantime, you can use the Coefficient method to simulate the behaviour you want.
Example:

d := NewFromFloat(5.45)
d.Coefficient().Int64()

[piyongcai]

// Coefficient returns the coefficient of the decimal.  It is scaled by 10^Exponent()
func (d Decimal) Coefficient() *big.Int {
	d.ensureInitialized()
	// we copy the coefficient so that mutating the result does not mutate the
	// Decimal.
	return big.NewInt(0).Set(d.value)
}

in Coefficient function, call big.NewInt(0).Set(d.value), this isn't a good idea.

[mwoss]

@piyongcai What do you mean by "this isn't a good idea"? Could you elaborate on that?

[clstb]

Had the same problem and drafted a PR for this @ #241.

[mwoss]

@clstb Maybe I'm still asleep, but what is the difference between your proposed implementation and an example I've showed earlier d.Coefficient().Int64()?

[clstb]

You were not asleep but I was apparently. I plugged your workaround into my test case and it errored. I thought this It is scaled by 10^Exponent() was the culprit since the value I got mismatched exactly by that.

Edit: After retrying it behaves how it should. Should have looked more carefully in the beginning 👍

[mwoss]

So I guess the most suitable option here would be to extend API by adding the CoefficientInt64 method or something similar then.
Also, I still would love to know what @piyongcai had in mind by telling "this isn't a good idea", it might be helpful tho.

[piyongcai]

// Coefficient returns the coefficient of the decimal.  It is scaled by 10^Exponent()
func (d Decimal) Coefficient() *big.Int {
	d.ensureInitialized()
	// we copy the coefficient so that mutating the result does not mutate the
	// Decimal.
	return big.NewInt(0).Set(d.value)
}

Because this method has a very low performance。
in fact， the flow method is better way.

// Int64Value returns the value.
func (d Decimal) Int64Value() int64 {
	return d.value.Int64()
}

In the usage scenario of protobuf, it is generally used for amount calculation, and the maximum decimal number is set to 4 bits.The message is defined as follows.

// Example: 12345.6789 -> { units = 12345, exp = 4} = 1.2345
message Decimal {

  // Whole units part of the amount
  int64 val = 1;

  // Nano units of the amount (10^-9)
  // Must be same sign as units
  int32 exp = 2;
}

I can convert between the two in the simplest way

[mwoss]

Yup, so let's expose new public method called CoefficientInt64 that would explicitly return coef as int64 value. It should resolve your issue and probably be helpful for others. I will craft the PR later today.

[piyongcai]

thanks

[mwoss]

#244 has been merged to main branch.
@piyongcai @clstb can you take a look if this is something you had in minds? :D

[piyongcai]

3ks,it's works