is not used in any concrete target

本文介绍了解决在macOS上使用CocoaPods安装MJExtension库时遇到的依赖未被使用的错误。通过在Podfile中指定项目目标的方式,成功解决了该问题。

重装了mac,使用cocoa pods的时候发生错误


提示  

The dependency `MJExtension` is not used in any concrete target.


然后加上两句话就可以了,有问题的也可以试试:


target 'myapp' do



end


把 需要安装的库放在这两句话中间就可以了, myapp 就是自己项目对应的名字


target ‘MedicalConsult’ do

pod 'AFNetworking', '~> 3.0'
pod 'MJExtension'

end

A typical usage scenario would be the following to enable a hist trigger, read its current contents, and then turn it off: # echo 'hist:keys=skbaddr.hex:vals=len' > \ /sys/kernel/debug/tracing/events/net/netif_rx/trigger # cat /sys/kernel/debug/tracing/events/net/netif_rx/hist # echo '!hist:keys=skbaddr.hex:vals=len' > \ /sys/kernel/debug/tracing/events/net/netif_rx/trigger The trigger file itself can be read to show the details of the currently attached hist trigger. This information is also displayed at the top of the 'hist' file when read. By default, the size of the hash table is 2048 entries. The 'size' parameter can be used to specify more or fewer than that. The units are in terms of hashtable entries - if a run uses more entries than specified, the results will show the number of 'drops', the number of hits that were ignored. The size should be a power of 2 between 128 and 131072 (any non- power-of-2 number specified will be rounded up). The 'sort' parameter can be used to specify a value field to sort on. The default if unspecified is 'hitcount' and the default sort order is 'ascending'. To sort in the opposite direction, append .descending' to the sort key. The 'pause' parameter can be used to pause an existing hist trigger or to start a hist trigger but not log any events until told to do so. 'continue' or 'cont' can be used to start or restart a paused hist trigger. The 'clear' parameter will clear the contents of a running hist trigger and leave its current paused/active state. Note that the 'pause', 'cont', and 'clear' parameters should be applied using 'append' shell operator ('>>') if applied to an existing trigger, rather than via the '>' operator, which will cause the trigger to be removed through truncation. - enable_hist/disable_hist The enable_hist and disable_hist triggers can be used to have one event conditionally start and stop another event's already-attached hist trigger. Any number of enable_hist and disable_hist triggers can be attached to a given event, allowing that event to kick off and stop aggregations on a host of other events. The format is very similar to the enable/disable_event triggers: enable_hist:<system>:<event>[:count] disable_hist:<system>:<event>[:count] Instead of enabling or disabling the tracing of the target event into the trace buffer as the enable/disable_event triggers do, the enable/disable_hist triggers enable or disable the aggregation of the target event into a hash table. A typical usage scenario for the enable_hist/disable_hist triggers would be to first set up a paused hist trigger on some event, followed by an enable_hist/disable_hist pair that turns the hist aggregation on and off when conditions of interest are hit: # echo 'hist:keys=skbaddr.hex:vals=len:pause' > \ /sys/kernel/debug/tracing/events/net/netif_receive_skb/trigger # echo 'enable_hist:net:netif_receive_skb if filename==/usr/bin/wget' > \ /sys/kernel/debug/tracing/events/sched/sched_process_exec/trigger # echo 'disable_hist:net:netif_receive_skb if comm==wget' > \ /sys/kernel/debug/tracing/events/sched/sched_process_exit/trigger The above sets up an initially paused hist trigger which is unpaused and starts aggregating events when a given program is executed, and which stops aggregating when the process exits and the hist trigger is paused again. The examples below provide a more concrete illustration of the concepts and typical usage patterns discussed above.
07-24
【博士论文复现】【阻抗建模、验证扫频法】光伏并网逆变器扫频与稳定性分析(包含锁相环电流环)(Simulink仿真实现)内容概要:本文档是一份关于“光伏并网逆变器扫频与稳定性分析”的Simulink仿真实现资源,重点复现博士论文中的阻抗建模与扫频法验证过程,涵盖锁相环和电流环等关键控制环节。通过构建详细的逆变器模型,采用小信号扰动方法进行频域扫描,获取系统输出阻抗特性,并结合奈奎斯特稳定判据分析并网系统的稳定性,帮助深入理解光伏发电系统在弱电网条件下的动态行为与失稳机理。; 适合人群:具备电力电子、自动控制理论基础,熟悉Simulink仿真环境,从事新能源发电、微电网或电力系统稳定性研究的研究生、科研人员及工程技术人员。; 使用场景及目标:①掌握光伏并网逆变器的阻抗建模方法;②学习基于扫频法的系统稳定性分析流程;③复现高水平学术论文中的关键技术环节,支撑科研项目或学位论文工作;④为实际工程中并网逆变器的稳定性问题提供仿真分析手段。; 阅读建议:建议读者结合相关理论教材与原始论文,逐步运行并调试提供的Simulink模型,重点关注锁相环与电流控制器参数对系统阻抗特性的影响,通过改变电网强度等条件观察系统稳定性变化,深化对阻抗分析法的理解与应用能力。
<think>Hmm, the user is asking why the 'Any' type schema isn't supported and how to resolve it. Let me unpack this carefully. First, I notice this is a follow-up to some schema-related issue, likely in a data processing context. The user seems frustrated since 'Any' type usually indicates flexible data handling, so its lack of support would be confusing. Looking at the references, especially [1] mentioning supported data types and [4] discussing Structured Streaming execution, this probably relates to systems like Spark or similar data engines. The core issue is type safety - systems need predictable schemas for optimization. The user might be trying to process semi-structured data (like JSON with mixed types) and hit this limitation. Their real need isn't just the "why" but practical workarounds. I should emphasize concrete solutions over theory. Key points to cover: - Performance implications of dynamic typing - Schema inference techniques - Trade-offs between flexibility and optimization - Specific examples for common systems like Spark The references hint at solutions: [3] shows pattern-based filtering which could help preprocess data, while [4]'s state tracking explains why schemas matter. I'll connect these to practical fixes. Should structure the answer: first explain the technical why (serialization, optimization, safety), then provide tiered solutions - from schema definition to data cleansing. The "how to resolve" part needs more weight than the explanation since that's their actual pain point. Also important to warn about runtime risks with workarounds. The user seems technical but might underestimate the performance cliffs with dynamic types.</think>在数据处理系统中,`Any` 类型模式不受支持主要源于**类型安全、性能优化和系统约束**的限制。以下是具体原因及解决方案: --- ### **一、`Any` 类型不受支持的原因** 1. **类型安全缺失** - `Any` 类型无法在编译期进行类型检查,可能导致运行时错误(如字段不匹配或操作无效)。 - 系统无法验证序列化/反序列化的正确性,增加数据损坏风险[^1][^4]。 2. **性能损耗** - 动态类型需要运行时类型推断,显著增加计算开销(如反射操作)。 - 无法使用基于固定模式的优化(如列式存储、向量化处理)[^4]。 3. **系统设计约束** - 引擎依赖明确模式进行状态跟踪(如 Spark Structured Streaming 的状态管理)[^4]。 - 分布式系统需确定的数据布局以优化网络传输和内存管理。 4. **序列化障碍** - 序列化框架(如 Avro/Protobuf)要求预定义模式,`Any` 类型无法生成有效的二进制协议。 --- ### **二、解决方案** #### 1. **明确定义 Schema** - **手动指定类型**:将动态数据转换为具体类型(如 `struct` 或 `map`)。 ```scala // Spark 示例:将动态字段转为 Map 类型 val schema = StructType(Seq( StructField("id", IntegerType), StructField("dynamic_data", MapType(StringType, StringType)) // 替代 Any )) ``` - **使用联合类型**:通过 `union` 类型覆盖有限的数据变体。 ```scala // 定义可接受的类型集合 val schema = StructType(Seq( StructField("value", DataTypes.createUnionType( Array(IntegerType, StringType, FloatType) )) )) ``` #### 2. **动态数据处理** - **分阶段处理**: 1. 用 `String` 或 `Binary` 类型接收原始数据。 2. 通过 UDF 解析并转换为具体类型。 ```python # PySpark 示例:解析 JSON 字符串 from pyspark.sql.functions import from_json, col json_schema = "a INT, b STRING" # 明确定义子模式 df = raw_df.withColumn("parsed", from_json(col("raw_data"), json_schema)) ``` #### 3. **模式演化与兼容性** - **Schema Registry**:使用 Avro Schema Registry 管理版本化模式,允许向后兼容的字段增减。 - **默认值处理**:为可选字段设置默认值,避免因字段缺失导致的错误。 ```json // Avro 示例:添加带默认值的可选字段 { "name": "new_field", "type": ["null", "int"], "default": null } ``` #### 4. **数据预处理** - **清洗动态字段**:移除或转换无法类型化的字段。 ```sql -- 移除无效字段 (HiveQL 示例) INSERT INTO cleaned_table SELECT id, CAST(dynamic_field AS MAP<STRING, STRING>) FROM raw_table WHERE dynamic_field IS NOT NULL; ``` #### 5. **系统级优化** - **关闭自动类型推断**:显式指定模式以避免开销。 ```scala // Spark 读取时强制指定模式 spark.read.schema(userDefinedSchema).json("data.json") ``` - **限制动态类型范围**:通过模式匹配缩小 `Any` 的范围[^3]。 ```xml <!-- Spring 风格的模式匹配:仅以 _dynamic 结尾的字段允许灵活类型 --> <beans default-autowire-candidates="*_dynamic"> ``` --- ### **三、关键设计原则** - **静态类型优先**:在入口处完成类型转换,保障核心流程的类型安全。 - **性能权衡**:动态类型处理应限定在边缘节点(如数据摄入层)。 - **容错机制**:对无法解析的数据启用死信队列(Dead Letter Queue)隔离。 > **示例场景**:若使用 Kafka 传输动态数据,可在消费者端将 `Any` 类型的消息转为 JSON 字符串,再用 Flink/Spark 按业务需求解析为具体类型,避免污染核心处理流程[^4]。 --- ### 相关问题 1. 如何在 Spark Structured Streaming 中处理动态变化的 JSON 模式? 2. 使用 `Any` 类型会导致哪些运行时性能问题?如何量化评估? 3. Avro 的 Schema Evolution 如何解决数据兼容性问题? 4. 在分布式系统中,为什么序列化协议(如 Protobuf)要求严格模式定义? 5. 如何设计死信队列(Dead Letter Queue)来捕获无法解析的动态数据? [^1]: 数据类型支持需参考具体引擎文档,如 Oracle GoldenGate 对类型的限制 [^4]: 状态跟踪和序列化是 Structured Streaming 执行策略的核心组件
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