Issues when translating from TType to TNumber and parameterized types within methods.
还没有人认领这个 Issue。
- 主要语言
- Java
- 星标
- 928
- 派生
- 227
- PR 合并指标
- 30 天内没有已合并 PR
描述
Many of the Java TF Ops use parameterized types for either TType, TNumber or both. Sometimes an Op uses <T extends TType> and sometimes another Op is using <T extends TNumber>. When writing a method that uses two different Ops that declare <T> differently, the compiler complains that T cannot be converted to the other type. It is interesting that TNumber is a subclass of TType. I have searched "Professor Google", but have not found an answer to this kind of problem.
TType to TNumber conversion is very common, especially if you are creating a base class with a common method signature across many similar objects. Sometimes, the subclass calls for a TType, sometimes a TNumber. The real problem, is when you have a common method such as public <T extends TType> Operand<T> call (Operand<T> input).
As a work around, let's say that you cast a TType to a TNumber (where <U extends TNumber>) as in:
@SuppressWarnings("unchecked")
Operand<U> uInput = (Operand<U>)input;
Now when you call something like tf.math.greater(uInput, otherValue);, the compiler complains:
no instance of type variables(s) exists so that T conforms to TNumber. That is because tf.math.greater uses <T extends TNumber> while other ops, like tf.nn.relu defines <T extends TType>.
Another way around this is to force erasure as in (Operand)value.
At a minimum, it would be nice if there were a convention like <T extends TType> and <U extends TNumber> consistently, but this may not solve all these kind of issues, as I have seen <U extends TType, T extends TType>, and <V extends TType, T extends TType, U extends TType>
The main issue that contributes to this problem is that the Ops require a mixture of types, so a higher level user is artificially juggling the situation by casting like above, or by forcing an erasure of the type.
IMO this situation is going to be confusing to the API user. I still haven't figured out a clean way to get around the issue when two method signatures use the same generic parameter in different ways.
Perhaps there is a better way. My gut feel is this is going to become a larger headache down the line.
The specific example I am running into at this time this problem is:
@Override
public Operand<T> call(Operand<T> input) {
@SuppressWarnings("unchecked")
Operand<U> uInput = (Operand<U>)input;
....
Operand<U> greater = tf.dtypes.cast(
tf.math.greater(uInput,
tf.dtypes.cast(tf.constant(threshold),
input.asTensor().dataType())), input.asTensor().dataType());
uInput = tf.math.mul(uInput, greater);
input = (Operand<T>)uInput;
...
贡献指南
从这里开始
- 先读完整个 Issue,再读项目的贡献指南。
- 在 Issue 下留言说明你要接手 —— 这能避免两个人做同样的事。
- Fork 仓库,在一个分支上完成修改。
- 提交 Pull Request,并在描述里引用这个 Issue 编号。
调研方向
未指定文件或测试。首先跟踪示例中的 Java TF Ops 签名 tf.math.greater、tf.nn.relu、tf.dtypes.cast 和 tf.math.mul,以及 Operand、TType 和 TNumber。完成的标准是:泛型 API 不一致问题已解决,或已通过一种可编译且避免不安全强制转换和类型擦除的方法得到清晰记录。
由索引模型根据 Issue 内容生成。
评估
- 技术栈
- java, tensorflow
- 领域
- api, backend-api-design
- Issue 类型
- 缺陷
- 难度
- 5/5
- 预计耗时
- 一周以上
- 活跃度
- 停滞
- 描述清晰度
- 需要澄清
- 新手友好度
- 25/100